tire

Abstract

To provide a tire that provides improved integrated performance of operation stability and noise performance during traveling at high speed.SOLUTION: A tire includes a tread portion provided with at least a first rubber layer that forms a tread surface and a second rubber layer that is located adjacent to the inner side in a tire radial direction of the first rubber layer. The tread portion includes: two or more circumferential groove continuously extending in a tire circumferential direction; a pair of shoulder land portions partitioned by the circumferential grooves and contact ends; and a center land portion located between the pair of shoulder land portions. The first rubber layer and the second rubber layer are formed of a rubber composition containing a rubber component. A ratio (H2 / H1) of a distance H2(mm) from the outermost surface of the tread portion to the deepest portion of the second rubber layer to a depth H1(mm) of the deepest portion of the circumferential groove is 0.40 to 0.90. When a complex elastic modulus (MPa) of the first rubber layer at 30°C is E*T and a complex elastic modulus (MPa) of the second rubber layer is E*B, E*B is larger than E*T, and a ratio (E*T / (H2 / H1)) of E*T to H2 / H1 is 6.0 or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to tires. [Background technology]

[0002] As a method for suppressing vibration noise (noise) of a tire during running, for example, a method is known in which the tread rubber of a pneumatic tire has a two-layer structure and foam rubber is used for the inner rubber layer (Patent Document 1).

[0003] Moreover, in recent years, there has been a strong demand in the tire market for steering stability, particularly during high-speed driving. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-156016 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present disclosure is to provide a tire with improved overall performance in terms of handling stability and noise performance during high-speed driving. [Means for solving the problem]

[0006] As a result of extensive research, it was discovered that the above problem can be solved by laminating two or more rubber layers in the tread portion of the tire and by making the complex elastic modulus of the rubber layers and the groove depth of the circumferential grooves have a predetermined relationship.

[0007] That is, the present disclosure relates to a tire having a tread portion including at least a first rubber layer constituting a tread surface and a second rubber layer adjacent to the first rubber layer on the radially inner side thereof, wherein the tread portion has two or more circumferential grooves extending continuously in the tire circumferential direction, a pair of shoulder land portions separated by the circumferential grooves and a ground contact edge, and a center land portion located between the pair of shoulder land portions, the first rubber layer and the second rubber layer are made of a rubber composition containing a rubber component, the ratio (H2 / H1) of the distance H2 (mm) from the outermost surface of the tread portion to the groove depth H1 (mm) of the deepest part of the circumferential groove is 0.40 to 0.90, and the complex modulus (MPa) of the first rubber layer at 30°C is E* T , the complex modulus (MPa) of the second rubber layer at 30 ° C. is E* B Then, E* B is E* T and the E* for the H2 / H1 T The ratio (E* T / (H2 / H1)) is 6.0 or more. [Effects of the Invention]

[0008] According to the present disclosure, a tire is provided that has improved overall performance in terms of handling stability and noise performance when traveling at high speeds. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view of an example of a tire according to an embodiment of the present disclosure. [Figure 2] 1 is a schematic diagram of a tire contact patch when the tread is pressed against a flat surface. [Figure 3] FIG. 2 is a schematic diagram of a contact patch of a tire according to another embodiment. [Figure 4] FIG. 2 is a schematic diagram of a contact patch of a tire according to another embodiment. [Figure 5] 1 is an enlarged cross-sectional view of a portion of a tread of a tire according to one embodiment of the present disclosure. [Figure 6]1 is an enlarged cross-sectional view of a portion of a tread of a tire according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] A tire according to one embodiment of the present disclosure is a tire having a tread portion including at least a first rubber layer constituting a tread surface and a second rubber layer adjacent to the first rubber layer on the radially inner side thereof, wherein the tread portion has two or more circumferential grooves extending continuously in the tire circumferential direction, a pair of shoulder land portions separated by the circumferential grooves and a ground contact edge, and a center land portion located between the pair of shoulder land portions, the first rubber layer and the second rubber layer are made of a rubber composition containing a rubber component, a ratio (H2 / H1) of a distance H2 from an outermost surface of the tread portion to a groove depth H1 of an innermost portion of the circumferential groove is 0.40 to 0.90, and a complex modulus (MPa) of the first rubber layer at 30°C is E* T , the complex modulus (MPa) of the second rubber layer at 30 ° C. is E* B Then, E* B is E* T and the E* for the H2 / H1 T The ratio (E* T / (H2 / H1)) is 6.0 or more.

[0011] By laminating two or more rubber layers in the tread portion of a tire and by setting the complex moduli of the rubber layers and the groove depths of the circumferential grooves in a predetermined relationship, the tire obtained has improved overall performance in terms of steering stability and noise performance during high-speed driving. The reason for this is thought to be as follows, without intending to be bound by theory.

[0012] If the entire tread is soft, it will collapse when cornering, impairing the transmission of force during acceleration and making acceleration when stepping on the accelerator less smooth.On the other hand, if the entire tread is hard, the tread will rise smoothly, but vibrations will be more easily transmitted, resulting in poor noise performance.

[0013] The tire of the present disclosure has the following features: (1) the land portion is divided into two or more rubber layers (preferably three or more) so that an interface is formed within the land portion, the second rubber layer is made harder than the first rubber layer, and the ratio (H2 / H1) of the distance H2 from the outermost surface of the tread portion to the outermost part of the second rubber layer to the groove depth H1 of the deepest part of the circumferential groove is set within a predetermined range, thereby making it possible to absorb vibrations within the first rubber layer, and at the same time, to generate a large force from the second rubber layer at the corner exit and transmit the force to the land portion, thereby enabling stable standing at the corner exit; (2) as H2 / H1 increases, the complex modulus of elasticity at 30°C (E* T ) is also large, it is possible to suppress the crushing of the first rubber layer. Furthermore, when H2 / H1 is small, the distance that vibrations travel from the road surface to the second rubber layer is short, but by softening the first rubber layer, it is possible to expect vibration absorption within the first rubber layer. These two factors working together are thought to achieve the remarkable effect of improving overall performance in terms of handling stability and noise performance during high-speed driving.

[0014] The rubber compositions constituting the first rubber layer and the second rubber layer preferably contain a filler containing silica, and the content of silica in the filler is preferably 50% by mass or more.

[0015] In the rubber composition constituting the first rubber layer and the second rubber layer, by setting the silica content in the filler to 50% by mass or more, it is possible to reduce the loss tangent tanδ of the rubber composition and reduce the phase difference from input to response, which is thought to make it easier to accelerate smoothly at the exit of a corner.

[0016] The tire of the present disclosure preferably includes, on the inner circumferential surface of the tire in the tread portion, one or more low-density members selected from the group consisting of a sealant layer, a noise-deadening material, and a three-dimensional mesh structure.

[0017] By providing low-density members on the inner circumferential surface of the tire, when vibrations are transmitted from the tread surface, these low-density members vibrate inside the tire, making it possible to offset the vibrations within the tread portion, and it is believed that the effects of the present disclosure can be achieved.

[0018] In the tire of the present disclosure, it is preferable that the amount of polymer in the rubber composition constituting the first rubber layer is 40 mass % or less, and that the amount of polymer in the rubber composition constituting the first rubber layer is greater than the amount of polymer in the rubber composition constituting the second rubber layer.

[0019] By setting the amount of polymer in the rubber composition constituting the first rubber layer to 40 mass% or less and making the amount of polymer in the rubber composition constituting the first rubber layer greater than the amount of polymer in the rubber composition constituting the second rubber layer, it is believed that transmission of vibrations by the polymer within the first rubber layer can be suppressed while making it easier to transmit force from the polymer chains of the second rubber layer to the first rubber layer.

[0020] In the tire of the present disclosure, the land area ratio within the contact patch is preferably 60 to 80%.

[0021] By keeping the land area ratio within the contact patch within the above range, it is believed that force is more easily transmitted across the entire tread when cornering, and that noise performance is also more easily improved because the areas that are locally subjected to vibrations from the road surface can be reduced.

[0022] In the tire of the present disclosure, it is preferable that the land area ratio in the contact patch is asymmetric about the tire equatorial plane.

[0023] In the tire of the present disclosure, it is preferable that the circumferential groove is not present on the tire equatorial plane, and the distance from the tire equatorial plane to the groove edge of the circumferential groove that is closest in the vehicle inner direction is different from the distance from the tire equatorial plane to the groove edge of the circumferential groove that is closest in the vehicle outer direction.

[0024] In the tire of the present disclosure, it is preferable that the groove area ratio in the shoulder land portion is larger than the groove area ratio in the center land portion.

[0025] By making the groove area ratio in the shoulder land portion larger than that in the center land portion, the shoulder land portion becomes more easily deformed during cornering, making it easier to generate force from the shoulder land portion. Also, in the center land portion that comes into contact with the tire during rolling, it is thought that it is easier to suppress an increase in localized input, which also makes it easier to improve noise performance.

[0026] In the tire of the present disclosure, it is preferable that the width direction length of at least one of the land portions gradually increases from the outer side toward the inner side in the tire radial direction. Also, in the tire of the present disclosure, the groove width on the tread surface of the circumferential groove positioned at the outermost side when mounted on a vehicle is L0, and the groove width at the 95% position of the deepest part of the groove bottom of the circumferential groove positioned at the outermost side when mounted on a vehicle is L1. Groove Width L 95 When L 95 It is preferable that / L0 is 0.20 to 0.80.

[0027] The width direction length of at least one of the land portions is gradually increased from the outer side toward the inner side in the tire radial direction (preferably, the L 95 By setting the ratio (L0) to 0.20 to 0.80, it is thought that multiple rubber layers are more likely to be formed uniformly on the land portion side during tire manufacturing, which makes it easier to suppress deterioration of noise performance.

[0028] Complex modulus E* of the first rubber layer at 30°C T is preferably 4.0 MPa or more.

[0029] E* T By setting the thickness within the above range, it is believed that the force transmitted from the second rubber layer can be more easily transmitted to the road surface.

[0030] The second rubber layer preferably has a tan δ at 30° C. of 0.25 or less.

[0031] By setting the 30° C. tan δ of the second rubber layer within the above range, it is possible to reduce the phase difference from input to response, which is thought to facilitate smooth acceleration at the corner exit.

[0032] The glass transition temperature of the first rubber layer is preferably −25° C. or higher.

[0033] By setting the glass transition temperature of the first rubber layer within the above range, it is thought that the energy loss corresponding to the frequency of vibrations generated during rolling during normal running can be increased, making it easier to absorb vibrations.

[0034] The second rubber layer preferably has a Shore hardness (Hs) of 50 to 80 as measured at a temperature of 23°C using a durometer type A in accordance with JIS K 6253-3:2012.

[0035] It is believed that by setting the Shore hardness (Hs) of the second rubber layer within the above range, good macro conformability can be easily obtained.

[0036] The modulus of the second rubber layer at 100% stretching is preferably greater than the modulus of the first rubber layer at 100% stretching.

[0037] By making the modulus of the second rubber layer at 100% stretch larger than the modulus of the first rubber layer at 100% stretch, it is possible to make it easier for the second rubber layer to generate large forces, which is thought to improve steering stability during high-speed driving.

[0038] <Definition> "Genuine rim" is the rim specified for each tire by the standard system that includes the standard on which the tire is based, such as "standard rim" for JATMA, "design rim" for TRA, and "measuring rim" for ETRTO. For tire sizes that are not specified in the above standard systems, it refers to the narrowest rim among the smallest diameter rims that can be mounted on the tire and do not cause air leakage between the rim and tire.

[0039] "Normal internal pressure" is the air pressure specified for each tire by each standard, including the standard on which the tire is based. For JATMA, it is the "maximum air pressure," for TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and for ETRTO, it is the "INFLATION PRESSURE." For tire sizes not specified in the above standard systems, the normal internal pressure is 250 kPa.

[0040] "Normal condition" refers to a state in which a tire is mounted on a normal rim, inflated to the normal internal pressure, and no load is applied. For tires of sizes not specified in the above-mentioned standard system, this refers to a state in which the tire is mounted on the smallest rim, inflated to 250 kPa, and no load is applied. Unless otherwise specified, the dimensions of each part of the tire (such as the tire section width Wt) are measured in the normal condition.

[0041] "Normal load" is the load specified for each tire by each standard in the standard system, including the standard on which the tire is based. For JATMA, it is "maximum load capacity," for TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and for ETRTO, it is "LOAD CAPACITY."

[0042] The "tread edge" is the outermost contact point in the tire width direction (left and right direction in Figure 2) when a normal tire is loaded in a normal state and in contact with a flat surface with a camber angle of 0 degrees. The tread edge Ti represents the tread edge that is on the inside of the vehicle when mounted on the vehicle, and the tread edge To represents the tread edge that is on the outside of the vehicle.

[0043] "Land portion" refers to the area in the tread portion that is partitioned by the tread contact edge and multiple circumferential grooves that extend continuously in the circumferential direction of the tire. For example, when there are two circumferential grooves, the land portion is divided into a pair of shoulder land portions and a center land portion sandwiched between them, and when there are three circumferential grooves, the center land portion is further divided into a land portion that will be on the inside of the vehicle when mounted on the vehicle and a land portion that will be on the outside of the vehicle.

[0044] The term "groove", including circumferential grooves and lateral grooves, refers to a recess having a width of at least 2.0 mm, whereas in this specification, the term "sipe" refers to a thin cut having a width of 2.0 mm or less, preferably 0.5 to 2.0 mm.

[0045] "Total contact patch area S" is the total area when all grooves are filled in the contact shape when the tread is pressed against a flat surface under normal conditions with a normal load and a camber angle of 0 degrees. "Land area ratio within the contact patch" refers to the ratio of the combined area of ​​the shoulder land area and center land area to the total contact patch area S.

[0046] The "groove area ratio in the shoulder land portion" refers to the total area of ​​the lateral grooves and / or sipes crossing the shoulder land portion relative to the total area of ​​the shoulder land portion. The "groove area ratio in the center land portion" refers to the total area of ​​the lateral grooves and / or sipes crossing the center land portion relative to the total area of ​​the center land portion.

[0047] The "land area S1 from the tire equatorial plane toward the vehicle's inner side" and the "land area S2 from the tire equatorial plane toward the vehicle's outer side" refer to the sum of the land areas that exist in the vehicle's inner side relative to the tire equatorial plane when the tire is mounted, and the sum of the land areas that exist in the vehicle's outer side, respectively.

[0048] The "groove depth H1 of the circumferential groove" is determined by the distance between the tread surface and an extension line of the deepest part of the groove bottom of the circumferential groove. Note that, for example, when there are multiple circumferential grooves 2, the groove depth H1 is the distance between the tread surface 10 and an extension line of the deepest part of the groove bottom of the circumferential groove 2 that has the deepest groove depth among the multiple circumferential grooves 2 (the circumferential groove 2 on the left side in FIG. 5).

[0049] "Distance H2 from the outermost surface of the tread portion to the outermost part of the second rubber layer" refers to the linear distance from the outermost surface of the tread portion on the tire equatorial plane C to the outermost part of the second rubber layer in the radial cross section of the tire when there are no circumferential grooves on the tire equatorial plane C, and refers to the linear distance from the outermost surface of the tread portion at the center in the tire width direction of the land portion closest to the tire equatorial plane to the outermost part of the second rubber layer in the case when there are circumferential grooves on the tire equatorial plane C. "Land portion closest to the tire equatorial plane" refers to the land portion having the groove edge closest to the tire equatorial plane C among the groove edges of circumferential grooves present on the tire equatorial plane C.

[0050] "Oil content" includes the amount of oil contained in oil-extended rubber.

[0051] <Measurement method> The "total area S of the contact patch," "total area of ​​shoulder land areas," "total area of ​​center land areas," and the "total area of ​​lateral grooves and / or sipes" that cross these land areas are values ​​calculated based on the contact shape. The contact shape is obtained by, for example, mounting a tire on a standard rim and maintaining the standard internal pressure, applying ink to the tread portion 1, and pressing the tire perpendicularly against cardboard or the like under a standard load to transfer the ink applied to the tread portion 1. Furthermore, based on the contact shape obtained, the total area of ​​the shoulder land areas is the sum of the areas of the shoulder land areas when all lateral grooves and sipes that cross the shoulder land areas are filled, and the total area of ​​the center land areas is the sum of the areas of the center land areas when all lateral grooves and sipes that cross the center land areas are filled.

[0052] The "land area S1 on the vehicle inward side from the tire equatorial plane" and the "land area S2 on the vehicle outward side from the tire equatorial plane" are calculated by dividing the contact shape with the tire equatorial plane at the center and summing the land area that exists on the vehicle inward side from the tire equatorial plane when the tire is mounted. Note that the land area is calculated based on the contact shape when all lateral grooves and sipes that cross those land areas are filled.

[0053] The "land area ratio in the contact patch" is determined by the ratio of the total area of ​​the shoulder land areas and the center land areas to the total contact patch area S, and is calculated, for example, as (S1+S2) / S.

[0054] "30°C E*" is the complex modulus (MPa) measured under the conditions of a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain of 1%. The sample for measuring the complex modulus is a vulcanized rubber composition having a length of 20 mm, a width of 4 mm, and a thickness of 1 mm. When cutting out a sample from a tire, the sample is cut out from the tread portion of the tire so that the long side is in the tire circumferential direction and the thickness direction is in the tire radial direction.

[0055] "30℃ tanδ" is the loss tangent measured under the conditions of a temperature of 30℃, a frequency of 10Hz, an initial strain of 5%, and a dynamic strain of 1%. The sample for measuring the loss tangent is prepared in the same manner as for 30℃E*.

[0056] The "glass transition temperature (Tg) of the rubber layer" is determined by measuring the temperature distribution curve of tan δ using a GABO Iplexer series under the conditions of a frequency of 10 Hz, an initial strain of 10%, an amplitude of ±0.5%, and a heating rate of 2°C / min, and is determined as the temperature corresponding to the largest tan δ value in the obtained temperature distribution curve (tan δ peak temperature). The sample for Tg measurement is prepared in the same manner as for 30°C E*.

[0057] "Shore hardness" is the Shore hardness (Hs) measured in accordance with JIS K 6253-3:2012 using a durometer type A at a temperature of 23°C. Samples for Shore hardness measurement are prepared by cutting out a sample from the tread portion so that the tire radial direction is the thickness direction. Measurements are also performed by pressing a measuring device against the sample from the contact surface side of the hardness measurement sample.

[0058] The "modulus at 100% stretch" is the tensile stress at 100% elongation in the grain direction (the rolling direction when forming a rubber sheet by extrusion or shearing) measured in accordance with JIS K 6251:2017 at a tensile speed of 3.3 mm / sec in an atmosphere of 23°C. The sample used to measure the modulus at 100% stretch is a dumbbell-shaped No. 7 vulcanized rubber test piece with a thickness of 1 mm. When cutting out the sample from a tire, it is cut out from the tread portion of the tire so that the tensile direction is in the tire circumferential direction and the tire radial direction is in the thickness direction.

[0059] The "polymer content (mass%)" in a rubber composition refers to the ratio of the total mass of the rubber components in the rubber composition to the total mass of the rubber composition, and can be determined by the following method. According to JIS K 6229:2015, a vulcanized rubber test piece is immersed in acetone for 24 hours to extract the acetone-soluble components. The test piece is then heated and dried to remove the solvent, and the mass of the vulcanized rubber test piece after the acetone-soluble components have been extracted is measured. Next, this vulcanized rubber test piece is subjected to thermal decomposition in a nitrogen stream by thermogravimetry according to JIS K 6226-1:2003, where the temperature is increased from room temperature to 750°C at a rate of 10°C / min, and the mass of the sample after thermal decomposition is measured. The "polymer content (mass%)" in the rubber composition can be determined by the difference between the mass of the vulcanized rubber test piece after the acetone-soluble components have been extracted and the mass of the sample after thermal decomposition, where the mass of the vulcanized rubber test piece before acetone extraction is taken as 100% by mass.

[0060] "Styrene content" is 1It is a value calculated by H-NMR measurement, and is applied to, for example, rubber components having repeating units derived from styrene, such as SBR. "Vinyl content (amount of 1,2-bonded butadiene units)" is a value calculated by infrared absorption spectroscopy in accordance with JIS K 6239-2:2017, and is applied to, for example, rubber components having repeating units derived from butadiene, such as SBR and BR. "Cis content (amount of cis-1,4-bonded butadiene units)" is a value calculated by infrared absorption spectroscopy in accordance with JIS K 6239-2:2017, and is applied to, for example, rubber components having repeating units derived from butadiene, such as BR.

[0061] The "weight average molecular weight (Mw)" can be determined by converting the measured value into a standard polystyrene equivalent value based on the value measured by gel permeation chromatography (GPC) (for example, GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMALTIPORE HZ-M manufactured by Tosoh Corporation). For example, this applies to SBR, BR, etc.

[0062] "N2SA of carbon black" is measured in accordance with JIS K 6217-2:2017. "N2SA of silica" is measured by the BET method in accordance with ASTM D3037-93.

[0063] A manufacturing procedure for a tire according to one embodiment of the present disclosure will be described in detail below. However, the following description is an example for explaining the present disclosure and is not intended to limit the technical scope of the present disclosure to the described range. In this specification, when a numerical range is indicated using "to" it is intended to include both ends of the numerical range.

[0064] [tire] Hereinafter, a tire according to an embodiment of the present disclosure will be described with reference to the drawings. Note that the embodiment described below is merely an example, and the tire according to the present disclosure is not limited to the embodiment described below.

[0065] FIG. 1 is a cross-sectional view of a tire taken along a plane passing through the tire rotation axis, and shows only the right side, divided by the tire centerline CL. The tire in FIG. 1 comprises a tread portion 1, sidewalls 32, bead portions 33, a carcass 34, a belt 35, and a band 36. The tread portion 1 is composed of two or more rubber layers, including a first layer 6 that forms the tread surface. The bead portions 33 include bead cores 31. The carcass 34 may include a carcass cord (not shown). The belt 35 may include a belt cord (not shown). The band 36 comprises an edge band 61 that covers only the edge portion of the belt 35, and a belt cord 36 that covers only the edge portion of the belt 35. 35 and a full band 62 that covers the entire area of ​​the tread portion 1. Both the edge band 61 and the full band 62 may include a band cord (not shown). Note that the illustration of each rubber layer in the tread portion 1 is omitted.

[0066] 2 is a schematic diagram of the contact patch of a tire when the tread portion 1 is pressed against a flat surface. A tread pattern that is specified for the orientation when mounted on a vehicle is formed on the tread portion 1. The tread pattern of the tread portion 1 is formed in an asymmetric shape with respect to the tire equator C.

[0067] The tread portion 1 has an outer tread edge To and an inner tread edge Ti. The outer tread edge To is located on the outer side of the vehicle (on the right side in FIG. 2) when mounted on the vehicle. The inner tread edge Ti is located on the inner side of the vehicle (on the left side in FIG. 2) when mounted on the vehicle.

[0068] The tread portion 1 has a plurality of circumferential grooves 11, 12, 13 that extend continuously in the circumferential direction C. In FIG. 2, three circumferential grooves 11, 12, 13 are provided. However, the number of circumferential grooves is not particularly limited, and may be, for example, two to five. Furthermore, in the present disclosure, the circumferential grooves 11, 12, 13 extend linearly along the circumferential direction C, but are not limited to this form, and may extend, for example, in a wave-like, sinusoidal, zigzag, or other shape along the circumferential direction C.

[0069] In this disclosure, the term "shoulder land portion" refers to a pair of land portions formed between the circumferential groove located outermost in the width direction W from the tire equator C and each tread edge To, Ti. In Fig. 2, there is provided an outer shoulder land portion 16 formed between the circumferential groove 12 located outermost when mounted on the vehicle and the outer tread edge To, and an inner shoulder land portion 17 formed between the circumferential groove 11 located innermost when mounted on the vehicle and the inner tread edge Ti.

[0070] In this disclosure, the term "center land portion" refers to all land portions sandwiched between the pair of shoulder land portions. In Fig. 2, there are provided an outer center land portion 18 formed between the circumferential groove 13 provided along the tire equator C and the circumferential groove 12 located on the outermost side when mounted on a vehicle, and an inner center land portion 19 formed between the circumferential groove 13 provided along the tire equator C and the circumferential groove 11 located on the innermost side when mounted on a vehicle, but the number of center land portions is not particularly limited and may be, for example, one to five.

[0071] In the present disclosure, the shoulder land portions 16, 17 and the center land portions 18, 19 are provided with lateral grooves and / or sipes that cross the land portions. In FIG. 2, the shoulder land portions 16, 17 have ends that are circumferential grooves. 11、12 A plurality of shoulder lateral grooves 21 opening to the circumferential grooves 11, 12 and a plurality of shoulder sipes 22 opening at one end to the circumferential grooves 11, 12 are provided, and a plurality of center sipes 23 opening at one end to the circumferential grooves 11, 13 are provided in the center land portions 18, 19.

[0072] From the viewpoint of noise performance, the groove area ratio in the shoulder land portion is preferably larger than the groove area ratio in the center land portion. The groove area ratio in the shoulder land portion is preferably 15 to 50%, more preferably 20 to 45%, and even more preferably 25 to 40%. The groove area ratio in the center land portion is preferably 10 to 45%, more preferably 15 to 40%, and even more preferably 20 to 35%.

[0073] The land area ratio within the contact patch is preferably 60 to 80%, more preferably 63 to 77%, and even more preferably 65 to 75%.

[0074] The land area ratio in the contact patch is preferably asymmetrical around the tire equatorial plane. The land area S1 from the tire equatorial plane toward the vehicle inner side is preferably smaller than the land area S2 from the tire equatorial plane toward the vehicle outer side. When S1 is smaller than S2, the rigidity in the vehicle outer side is greater than that in the vehicle inner side, and the cornering force ratio (CF ratio) of the rear to the front increases, which is thought to improve linearity and steering stability. The ratio (S1 / S) of the land area S1 from the tire equatorial plane toward the vehicle inner side to the total contact patch area S is preferably 0.30 to 0.40, more preferably 0.32 to 0.38. The ratio (S2 / S) of the land area S2 from the tire equatorial plane toward the vehicle outer side to the total contact patch area S is preferably 0.30 to 0.40, more preferably 0.32 to 0.38.

[0075] Fig. 3 is a schematic diagram of a tire contact patch according to another embodiment. In Fig. 3, there are three circumferential grooves 11, 12, and 13 that extend continuously in the circumferential direction C. The groove width of the circumferential groove 11 provided in the vehicle inner side from the tire equatorial plane is wider than the groove width of the circumferential groove 12 provided in the vehicle outer side from the tire equatorial plane, and the land area S1 from the tire equatorial plane in the vehicle inner side is smaller than the land area S2 from the tire equatorial plane in the vehicle outer side. The shoulder land portions 16 and 17 have ends that are in contact with the circumferential grooves. 11、12 A plurality of shoulder lateral grooves 21 opening to the circumferential grooves 11, 12 and a plurality of shoulder sipes 22 opening at one end to the circumferential grooves 11, 12 are provided, and a plurality of center sipes 23 opening at one end to the circumferential grooves 11, 13 are provided in the center land portions 18, 19.

[0076] In the tire of the present disclosure, it is preferable that the circumferential groove is not present on the tire equatorial plane, and the distance from the tire equatorial plane to the groove edge of the circumferential groove closest to the vehicle inboard direction is different from the distance from the tire equatorial plane to the groove edge of the circumferential groove closest to the vehicle outboard direction. The distance W2 from the tire equatorial plane to the groove edge of the circumferential groove closest to the vehicle inboard direction is preferably greater than the distance W3 from the tire equatorial plane to the groove edge of the circumferential groove closest to the vehicle outboard direction. By making W2 greater than W3, it is possible to increase the rigidity of the tire in the vehicle outboard direction, and when centrifugal force is applied during cornering, the tread portion can deform mainly toward the inner side of the vehicle and make contact with the road, which is thought to make it easier to efficiently transmit force to the road surface. The ratio (W2 / W1) of the distance W2 from the tire equatorial plane to the groove edge of the circumferential groove closest to the vehicle inboard side to the distance W1 from the tire equatorial plane to the tread ground contact edge is preferably 0.07 to 0.30, more preferably 0.09 to 0.25, even more preferably 0.10 to 0.20, and particularly preferably 0.12 to 0.20. The ratio (W3 / W1) of the distance W3 from the tire equatorial plane to the groove edge of the circumferential groove closest to the vehicle outboard side to the distance W1 from the tire equatorial plane to the tread ground contact edge is preferably 0.05 to 0.25, more preferably 0.08 to 0.22, even more preferably 0.10 to 0.20, and particularly preferably 0.10 to 0.18.

[0077] Fig. 4 is a schematic diagram of a tire contact patch according to another embodiment. In Fig. 4, there are four circumferential grooves 11, 12, 13, and 14 extending continuously in the circumferential direction C, and no circumferential grooves are present on the tire equatorial plane. The distance W2 from the tire equatorial plane to the groove edge of the circumferential groove 13 closest to the vehicle inner side is greater than the distance W3 from the tire equatorial plane to the groove edge of the circumferential groove 14 closest to the vehicle outer side. Furthermore, the groove width of the circumferential groove 13 is greater than the groove widths of the other circumferential grooves 11, 12, and 14, and the land area S1 from the tire equatorial plane to the vehicle inner side is smaller than the land area S2 from the tire equatorial plane to the vehicle outer side. The shoulder land portions 16 and 17 each have an end that is in contact with the circumferential groove. 11、12The tire has a plurality of shoulder lateral grooves 21 that open to the circumferential grooves 11, 12 and a plurality of shoulder sipes 22 that open at one end to the circumferential grooves 11, 12, and the outer center land portion 18 and the inner center land portion 19 have a plurality of center sipes 23 that open at one end to the circumferential grooves 11, 12, 13, 14. In FIG. 4, the center land portion 20 located on the tire equatorial plane is formed as a plain rib that has no lateral grooves or sipes, but is not limited to this.

[0078] <Low-density materials> The tire of the present disclosure may include a low-density member on the inner circumferential surface of the tire tread portion. The low-density member is not particularly limited as long as it has the effect of canceling vibrations transmitted to the inner circumferential surface of the tire through resonance. Examples of such low-density members include a sealant layer used to prevent punctures, a sound-damping body, and a three-dimensional mesh structure.

[0079] The low-density member can exert its effect by being disposed on the inner circumferential surface of the tire in the tread portion. The thickness of the low-density member in the radial direction of the tire, the width of the low-density member in the axial direction of the tire, or the volume, cross-sectional area, and other properties of the low-density member may vary depending on the type of the low-density member, but can be determined appropriately by a person skilled in the art.

[0080] The low-density member may be used alone or in combination with a plurality of low-density members. Examples of such combinations include, but are not limited to, first providing a sealant layer on the inner circumferential surface of the tire tread, and then providing a sound-damping body or a three-dimensional mesh structure thereon.

[0081] (sealant layer) As the sealant layer, a layer generally used on the inner peripheral surface of the tire tread portion for puncture prevention can be suitably used. Specific examples of such sealant layers include those described in JP 2020-23152 A. The thickness of the sealant layer is usually preferably 1 to 10 mm. The width of the sealant layer is usually preferably 85 to 115%, and more preferably 95 to 105%, of the maximum width of the belt layer.

[0082] (sound damping body) Any noise damper can be suitably used as long as it can exert a noise-damping effect in the tire cavity. Specific examples of such noise dampers include those described in JP 2019-142503 A. The noise damper is made of, for example, a porous sponge material. Sponge materials are spongy porous structures, and include, for example, so-called sponges with open cells formed by foaming rubber or synthetic resin, as well as web-like structures formed by intertwining and connecting animal fibers, plant fibers, synthetic fibers, etc. Furthermore, "porous structures" include those with not only open cells but also closed cells. An example of a noise damper is an open-cell sponge material made of polyurethane. Suitable sponge materials include synthetic resin sponges such as ether-based polyurethane sponge, ester-based polyurethane sponge, and polyethylene sponge, and rubber sponges such as chloroprene rubber sponge (CR sponge), ethylene propylene rubber sponge (EDPM sponge), and nitrile rubber sponge (NBR sponge). In particular, polyurethane-based or polyethylene-based sponges, including ether-based polyurethane sponges, are preferred from the standpoints of sound-damping properties, light weight, foam adjustability, durability, etc.

[0083] The noise-damping body 9 is a long, strip-like body with a bottom surface fixed to the inner cavity surface of the tread portion, extending in the tire circumferential direction. The outer ends of the noise-damping body 9 may be butted together to form a generally circular ring shape, or the outer ends may be spaced apart in the circumferential direction. The noise-damping body 9 has substantially the same cross-sectional shape at every circumferential position except for the outer ends. This cross-sectional shape is preferably flat and oblong, with a height smaller than the axial width of the tire, to prevent collapse and deformation during running. In particular, providing the radially inner side with grooves 7 extending continuously in the circumferential direction increases the surface area of ​​the noise-damping body, enabling it to absorb more resonance energy and improve heat dissipation, thereby suppressing temperature rise in the sponge material.

[0084] The glass transition temperature (Tg) of the sound damper is preferably -55°C to -45°C from the viewpoint of maintaining good durability and flexibility. If the sound damper maintains its flexibility at low temperatures, the sound damper will effectively convert air vibration energy into thermal energy, for example, even when driving in cold weather, and driving noise will be sufficiently reduced. In this specification, Tg is a value measured using a differential scanning calorimeter SC Q2000 manufactured by TA Instruments in accordance with ASTM D 6604 (published in 2013).

[0085] The density of the sound-damping body is set to 1.0 x 10 in order to reduce running noise around 250 Hz without increasing the weight of the tire. -2 g / cm 3 ~4.0×10 -2 g / cm 3 It is preferable that:

[0086] From the viewpoint of sufficient conversion of air vibration energy, the volume of the noise damper is desirably 0.4 to 30% of the total volume of the tire cavity. The volume of the noise damper refers to the apparent total volume of the noise damper, which is the volume determined from the outer shape including the air bubbles inside. In this specification, the total volume V of the tire cavity is approximately calculated using the following formula when the pneumatic tire is mounted on a regular rim, inflated to the regular internal pressure, and in a normal, unloaded state. V=A×{(Di-Dr) / 2+Dr}×π In the above formula, "A" is the cross-sectional area of ​​the tire cavity obtained by CT scanning the tire-rim assembly in the normal state, "Di" is the maximum outer diameter of the tire cavity surface in the normal state, "Dr" is the rim diameter, and "π" is the ratio of the circumference of a tire to its circumference.

[0087] The tensile strength of the noise damper is preferably 70 to 115 kPa from the viewpoint of durability of the noise damper.

[0088] (3D mesh structure) Generally, any three-dimensional mesh structure can be suitably used as long as it acts as a sound-absorbing material. Specific examples of such sound-absorbing materials include those described in JP 2018-90131 A. More specifically, the three-dimensional mesh structure is formed by irregularly entangling multiple filaments made of molten resin and welding the entangled portions.

[0089] The three-dimensional mesh structure is preferably fixed to the tire cavity. The method for fixing the three-dimensional mesh structure to the tire cavity is not particularly limited, and may be, for example, by adhering to the inner surface of the tire with an adhesive or the like, but it may also be fixed by the sealant material constituting the sealant layer, and is preferably fixed in this manner.

[0090] The thickness of the three-dimensional mesh structure is not particularly limited, but is preferably 1.0 to 150 mm, more preferably 30 to 120 mm. The width is not particularly limited, but is preferably 50 to 95% of the width of the sealant layer, more preferably 60 to 90%, because this provides a more suitable effect.

[0091] From the viewpoint of efficient sound absorption performance, the cross-sectional area ratio of the three-dimensional mesh structure (i.e., (cross-sectional area of ​​three-dimensional mesh structure / cross-sectional area of ​​tire cavity) × 100) is preferably 2 to 90%, more preferably 5 to 70%, and even more preferably 20 to 70%. Here, the cross-sectional area ratio can be changed, for example, by changing the width or thickness of the three-dimensional mesh structure. The cross-sectional area of ​​the three-dimensional mesh structure refers to the apparent cross-sectional area of ​​the three-dimensional mesh structure, which is determined from the outer shape of the three-dimensional mesh structure including internal cavities. The cross-sectional area of ​​the three-dimensional mesh structure is calculated by dividing the volume of the three-dimensional mesh structure by the average thickness (thickness in the tire radial direction) of the three-dimensional mesh structure. Here, the volume of the three-dimensional mesh structure refers to the apparent total volume of the three-dimensional mesh structure, which is determined from the outer shape of the three-dimensional mesh structure including internal cavities. Furthermore, the average thickness of the three-dimensional mesh structure also refers to the average thickness determined from the outer shape of the three-dimensional mesh structure including internal cavities. In this specification, the cross-sectional area of ​​the tire cavity is calculated by dividing the total volume of the tire cavity by the height of the tire cavity in the tire radial direction.

[0092] The apparent density of the three-dimensional mesh structure is 1.0 to 25.0 × 10 from the viewpoint of efficient sound absorption performance. -2 g / cm 3 is preferable, and 2.0 to 20.0 × 10 -2 g / cm 3 More preferably, 3.0 to 10.0 × 10 -2 g / cm 3 is more preferable. In this specification, the apparent density refers to a density calculated by regarding the cavities present inside the three-dimensional mesh structure as part of the volume of the three-dimensional mesh structure, and is calculated by dividing the mass of the three-dimensional mesh structure by the total apparent volume of the three-dimensional mesh structure (the volume determined from the outer shape of the three-dimensional mesh structure including the internal cavities). Specifically, the apparent density can be calculated by using the three-dimensional mesh structure to prepare a cubic measurement sample having an approximate size of 1 m x 1 m x 1 m, and measuring the mass of the prepared measurement sample.

[0093] 5 is an enlarged cross-sectional view showing a portion of the tire tread. In FIG. 5, the vertical direction is the tire radial direction, the horizontal direction is the tire width direction, and the direction perpendicular to the paper surface is the tire circumferential direction.

[0094] As shown in the figure, the tread portion of a tire of the present disclosure includes a first rubber layer 6 and a second rubber layer 7, and may include a third rubber layer 8 (hereinafter, these may be simply referred to as the "first layer 6," "second layer 7," or "third layer 8"). The outer surface of the first layer 6 constitutes the tread surface 3, the second layer 7 is adjacent to the radially inner side of the first layer 6, and the third layer 8 is adjacent to the radially inner side of the second layer 7. The first layer 6 typically corresponds to a cap tread. The third layer 8 typically corresponds to a base tread or undertread. The second layer 7 does not have a specific shape, and may therefore be either a base tread or an undertread. Furthermore, one or more rubber layers may be present between the third layer 8 and the belt layer, as long as the objectives of the present disclosure are achieved.

[0095] In Fig. 5, the deepest portion of the groove bottom of the circumferential groove 1 having the deepest groove depth among the plurality of circumferential grooves 1 is formed so as to be located radially inward of the outermost portion of the second layer 7 in the land portion 2 adjacent to that circumferential groove. In other words, an extension line 5 of the deepest portion of the groove bottom of the circumferential groove 1 having the deepest groove depth among the plurality of circumferential grooves 1 is located radially inward of an extension line 9 of the outermost portion of the second layer 7 in the land portion 2 adjacent to that circumferential groove. Directly below (radially inner in the tire) the circumferential groove 1 having the deepest groove depth among the plurality of circumferential grooves 1, there is a recessed portion recessed radially inward of the outermost portion of the second layer 7 in the land portion 2 adjacent to that circumferential groove, and a portion of the first layer 6 is formed with a predetermined thickness in the recessed portion of the second layer 7.

[0096] From the viewpoint of the effects of the present disclosure, the ratio (H2 / H1) of the distance H2 (mm) from the outermost surface of the tread portion to the groove depth H1 (mm) of the deepest portion of the circumferential groove is 0.40 or more, preferably 0.42 or more, more preferably 0.44 or more, even more preferably 0.46 or more, and particularly preferably 0.48 or more. On the other hand, H2 / H1 is 0.90 or less, preferably 0.80 or less, more preferably 0.75 or less, even more preferably 0.70 or less, and particularly preferably 0.65 or less.

[0097] E* for H2 / H1 T The ratio (E* T From the viewpoint of the effects of the present disclosure, E* relative to H2 / H1 is 6.0 or more, preferably 7.0 or more, more preferably 8.0 or more, even more preferably 9.0 or more, and particularly preferably 10 or more. T The ratio (E* T The upper limit of H2 / H1 is not particularly limited, but can be set to, for example, 30 or less, 25 or less, 20 or less, or 15 or less.

[0098] In the present disclosure, it is preferable that the width direction length of at least one of the land portions gradually increases from the outer side toward the inner side in the tire radial direction. This facilitates the formation of multiple rubber layers uniformly on the side surfaces of the land portions during tire manufacturing, which is thought to facilitate the suppression of deterioration of noise performance in the later stages of wear. Note that, although the groove wall 7 of the circumferential groove in the present disclosure extends linearly from the outer side toward the inner side in the tire radial direction, it is not limited to this form and may extend, for example, in a curved or stepped manner.

[0099] The groove width L0 of the circumferential groove 12 located at the outermost position on the tread surface when mounted on a vehicle is 95% of the deepest part of the groove bottom of the circumferential groove 12. Groove Width L 95 The ratio (L 95 / L0) is preferably 0.20 or more, more preferably 0.25 or more, even more preferably 0.30 or more, and particularly preferably 0.35 or more, from the viewpoint of the effects of the present disclosure. 95 / L0 is preferably equal to or less than 0.80, more preferably equal to or less than 0.70, further preferably equal to or less than 0.65, and particularly preferably equal to or less than 0.60. Note that in Fig. 6, the individual rubber layers are not shown.

[0100] First layer 6 30℃E*(E* T ) is preferably 3.0 MPa or more, more preferably 4.0 MPa or more, even more preferably 5.0 MPa or more, and particularly preferably 6.0 MPa or more. T It is believed that by setting the value of E*(E*) in the above range, the force transmitted from the second layer 7 can be easily transmitted to the road surface. B ) is preferably 4.0 MPa or more, more preferably 5.0 MPa or more, even more preferably 6.0 MPa or more, and particularly preferably 7.0 MPa or more, from the viewpoint of steering stability at high speeds. The 30°C E* of the third layer 8 is preferably 3.0 MPa or more, more preferably 4.0 MPa or more, even more preferably 5.0 MPa or more, and particularly preferably 6.0 MPa or more. On the other hand, the 30°C E* of the first layer 6, the second layer 7, and the third layer 8 is preferably 25 MPa or less, more preferably 20 MPa or less, and even more preferably 18 MPa or less, from the viewpoint of wet grip performance. The difference in complex modulus at 30°C between adjacent rubber layers is preferably 1.0 MPa or more, more preferably 1.5 MPa or more, and even more preferably 2.0 MPa or more. By setting the difference in complex modulus at 30°C between adjacent rubber layers within the above range, resonance between adjacent rubber layers can be more effectively suppressed. The 30°C E* of each rubber layer can be adjusted appropriately by the types and amounts of rubber components, fillers, softeners, etc. (particularly softeners) described below.

[0101] The 30°C tan δ of the first layer 6 is preferably 0.25 or less, more preferably 0.24 or less, even more preferably 0.23 or less, and particularly preferably 0.22 or less. The 30°C tan δ of the second layer 7 is preferably 0.25 or less, more preferably 0.24 or less, even more preferably 0.23 or less, and particularly preferably 0.22 or less. The 30°C tan δ of the third layer 8 is preferably 0.25 or less, more preferably 0.24 or less, even more preferably 0.23 or less, and particularly preferably 0.22 or less. By setting the 30°C tan δ within the above range, the phase difference from input to response can be reduced, which is thought to facilitate smooth acceleration at corner exits. On the other hand, from the viewpoint of wet grip performance, the 30°C tan δ of the rubber composition constituting the first layer 6, second layer 7, and third layer 8 is preferably 0.10 or more, more preferably 0.12 or more, and even more preferably 0.14 or more. The 30° C. tan δ of each rubber layer can be adjusted appropriately by the types and amounts of rubber components, fillers, softeners, etc. (particularly softeners) described below.

[0102] The Tg of the first layer 6 is preferably -25°C or higher, more preferably -20°C or higher, and even more preferably -15°C or higher. By setting the glass transition temperature of the first layer 6 within the above range, it is believed that the energy loss corresponding to the frequency of vibrations generated during rolling during normal running can be increased, making it easier to absorb vibrations. The Tg of the second layer 7 is preferably -30°C or higher, more preferably -25°C or higher, and even more preferably -20°C or higher. While there are no particular upper limits for the Tg of the first layer 6 and the second layer 7, it is preferably 20°C or lower, more preferably 15°C or lower, and even more preferably 10°C or lower. The Tg of each rubber layer can be adjusted appropriately by changing the type and amount of the rubber components, etc., described below.

[0103] The Shore hardness (Hs) of the first layer 6 is preferably 80 or less, more preferably 75 or less, and even more preferably 70 or less. The Shore hardness (Hs) of the second layer 7 is preferably 80 or less, more preferably 75 or less, and even more preferably 70 or less. By setting the Shore hardness (Hs) of the first layer 6 and the second layer 7 within the above range, it is believed that reaction force can be easily obtained without impairing road surface conformity. On the other hand, from the viewpoint of maintaining the block rigidity of the tire, the Shore hardness (Hs) of the first layer 6 and the second layer 7 is preferably 50 or more, and more preferably 55 or more. The rubber hardness of each rubber layer can be appropriately adjusted by changing the type and amount of rubber components, fillers, softeners, etc., which will be described later.

[0104] The modulus of the first layer 6 at 100% stretch is preferably 1.0 MPa or more, more preferably 1.2 MPa or more, even more preferably 1.4 MPa or more, and particularly preferably 1.6 MPa or more. The modulus of the second layer 7 at 100% stretch is preferably 1.0 MPa or more, more preferably 1.2 MPa or more, even more preferably 1.4 MPa or more, and particularly preferably 1.6 MPa or more. The upper limit of the modulus of the first layer 6 and the second layer 7 at 100% stretch is not particularly limited, but is typically 4.0 MPa or less, preferably 3.5 MPa or less. In the present disclosure, the modulus of the second layer 7 at 100% stretch is preferably greater than the modulus of the first layer 6 at 100% stretch. By making the modulus of the second layer 7 at 100% stretch greater than the modulus of the first layer 6 at 100% stretch, it is believed that the second layer 7 can more easily generate large forces, thereby improving handling stability at high speeds. The difference between the modulus of the second layer 7 at 100% stretch and the modulus of the first layer 6 at 100% stretch is preferably 0.1 MPa or more, more preferably 0.2 MPa or more, and even more preferably 0.3 MPa or more. The modulus of each rubber layer at 100% stretch can be appropriately adjusted by changing the types and amounts of rubber components, fillers, softeners, etc., which will be described later.

[0105] [Rubber composition for tread] The tread portion of the present disclosure is composed of two or more rubber layers, and the complex modulus E* of the second layer at 30°C Bis the complex modulus E* of the first layer at 30°C T The rubber compositions constituting each layer of the tread portion can be produced using the raw materials described below in accordance with the required complex modulus at 30°C, etc., as will be explained in detail below.

[0106] <Rubber component> The rubber composition according to the present disclosure preferably uses a diene rubber as the rubber component. Examples of diene rubber include isoprene rubber, butadiene rubber (BR), styrene butadiene rubber (SBR), styrene isoprene rubber (SIR), styrene isoprene butadiene rubber (SIBR), chloroprene rubber (CR), and acrylonitrile butadiene rubber (NBR). These diene rubber components may be used alone or in combination of two or more.

[0107] The content of the diene rubber in 100% by mass of the rubber component is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more. The rubber component may also consist solely of the diene rubber.

[0108] The rubber composition according to the present disclosure preferably contains, as a rubber component, at least one rubber selected from the group consisting of isoprene-based rubber, styrene-butadiene rubber (SBR), and butadiene rubber (BR). The rubber composition constituting the rubber layers (at least the first and second layers in the present disclosure) intended to come into contact with the road surface due to wear during driving preferably contains, as a rubber component, SBR, more preferably SBR and BR, and even more preferably isoprene-based rubber, SBR, and BR, and may be a rubber component consisting solely of isoprene-based rubber, SBR, and BR. On the other hand, the rubber composition constituting the rubber layers not intended to come into contact with the road surface due to wear during driving preferably contains, as a rubber component, isoprene-based rubber, more preferably isoprene-based rubber and BR, and may be a rubber component consisting solely of isoprene-based rubber and BR. The third layer according to the present disclosure may be a rubber layer intended to come into contact with the road surface during driving, or may be a rubber layer not intended to come into contact with the road surface during driving, depending on the application and structure of the tire.

[0109] (Isoprene rubber) Examples of isoprene-based rubbers that can be used include those commonly used in the tire industry, such as isoprene rubber (IR) and natural rubber. Natural rubber includes unmodified natural rubber (NR) as well as modified natural rubbers such as epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), highly purified natural rubber, and grafted natural rubber. These isoprene-based rubbers may be used alone or in combination of two or more.

[0110] The NR is not particularly limited, and those commonly used in the tire industry can be used, such as SIR20, RSS#3, and TSR20.

[0111] When an isoprene-based rubber is contained in a rubber composition constituting a rubber layer intended to come into contact with the road surface during running, the content of the isoprene-based rubber in 100% by mass of the rubber component is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, and particularly preferably 20% by mass or less, from the viewpoint of wet grip performance. There is no particular lower limit to the content, and it can be, for example, 1% by mass or more, 3% by mass or more, 5% by mass or more, or 10% by mass or more.

[0112] When an isoprene-based rubber is contained in a rubber composition constituting a rubber layer that is not intended to come into contact with the road surface during running, the content of the isoprene-based rubber in 100% by mass of the rubber component is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more. There is no particular upper limit to the content.

[0113] (SBR) The SBR is not particularly limited, and examples thereof include solution-polymerized SBR (S-SBR), emulsion-polymerized SBR (E-SBR), and modified SBRs thereof (modified S-SBR, modified E-SBR). Modified SBRs include SBRs whose ends and / or main chains are modified, and modified SBRs coupled with tin, silicon compounds, etc. (condensates, those having a branched structure, etc.). Of these, S-SBR and modified SBR are preferred. Furthermore, hydrogenated products of these SBRs (hydrogenated SBR) can also be used.

[0114] The SBRs listed above may be used alone or in combination of two or more. As the SBRs listed above, for example, commercially available products from Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Co., Ltd., ZS Elastomers Co., Ltd., etc. can be used.

[0115] From the viewpoints of wet grip performance and abrasion resistance, the styrene content of SBR is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more. From the viewpoints of temperature dependency of grip performance and blow resistance, the styrene content is preferably 60% by mass or less, more preferably 55% by mass or less, and even more preferably 50% by mass or less. In this specification, the styrene content of SBR is 1 It is calculated by H-NMR measurement.

[0116] The vinyl content of SBR is preferably 10 mol% or more, more preferably 15 mol% or more, and even more preferably 20 mol% or more, from the viewpoints of ensuring reactivity with silica, wet grip performance, rubber strength, and abrasion resistance. Furthermore, the vinyl content of SBR is preferably 70 mol% or less, more preferably 65 mol% or less, and even more preferably 60 mol% or less, from the viewpoints of preventing an increase in temperature dependency, elongation at break, and abrasion resistance. In this specification, the vinyl content of SBR is measured by the above-mentioned measurement method.

[0117] From the viewpoint of wet grip performance, the weight average molecular weight (Mw) of SBR is preferably 200,000 or more, more preferably 250,000 or more. From the viewpoint of crosslinking uniformity, the weight average molecular weight is preferably 2,000,000 or less, more preferably 1,800,000 or less, and even more preferably 1,500,000 or less. In this specification, the weight average molecular weight of SBR is measured by the above-mentioned measurement method.

[0118] When SBR is contained in a rubber composition constituting a rubber layer intended to come into contact with a road surface during driving, the content of SBR in 100% by mass of the rubber component is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, and particularly preferably 40% by mass or more, from the viewpoint of wet grip performance. The upper limit of the SBR content in the rubber component is not particularly limited, and can be, for example, 90% by mass or less, 80% by mass or less, or 70% by mass or less. In addition, the content of SBR in the rubber component in a rubber composition constituting a rubber layer not intended to come into contact with a road surface during driving is not particularly limited.

[0119] (BR) The BR is not particularly limited, and can be one commonly used in the tire industry, such as BR with a cis content of less than 50 mol% (low-cis BR), BR with a cis content of 90 mol% or more (high-cis BR), rare earth butadiene rubber (rare earth BR) synthesized using a rare earth catalyst, BR containing syndiotactic polybutadiene crystals (SPB-containing BR), modified BR (high-cis modified BR, low-cis modified BR), etc. These BRs may be used alone or in combination of two or more.

[0120] As the high-cis BR, for example, commercially available products from Zeon Corporation, Ube Industries, Ltd., JSR Corporation, etc. can be used. The inclusion of high-cis BR can improve low-temperature properties and wear resistance. The cis content is preferably 95 mol% or more, more preferably 96 mol% or more, even more preferably 97 mol% or more, and particularly preferably 98 mol% or more. In this specification, the cis content is measured by the above-mentioned measurement method.

[0121] As the modified BR, a modified butadiene rubber (modified BR) whose terminals and / or main chain are modified with a functional group containing at least one element selected from the group consisting of silicon, nitrogen, and oxygen is preferably used.

[0122] Other examples of modified BR include tin-modified BR, which is obtained by polymerizing 1,3-butadiene with a lithium initiator and then adding a tin compound, and in which the terminals of the modified BR molecule are further bonded with a tin-carbon bond (tin-modified BR).Modified BR may be either non-hydrogenated or hydrogenated.

[0123] From the viewpoint of abrasion resistance, the weight-average molecular weight (Mw) of the BR is preferably 300,000 or more, more preferably 350,000 or more, and even more preferably 400,000 or more. From the viewpoint of crosslinking uniformity, it is preferably 2,000,000 or less, more preferably 1,000,000 or less. The weight-average molecular weight of the BR can be determined in terms of standard polystyrene based on measurements obtained by gel permeation chromatography (GPC) (for example, GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMALTIPORE HZ-M manufactured by Tosoh Corporation).

[0124] When BR is contained in a rubber composition constituting a rubber layer that is assumed to come into contact with the road surface during running, the content of BR in 100% by mass of the rubber component is preferably 60% by mass or less, more preferably 50% by mass or less, even more preferably 45% by mass or less, and particularly preferably 40% by mass or less, from the viewpoint of wet grip performance. There is no particular lower limit for the content, and it can be, for example, 1% by mass or more, 3% by mass or more, 5% by mass or more, 10% by mass or more, or 15% by mass or more.

[0125] When BR is contained in a rubber composition constituting a rubber layer that is not intended to come into contact with the road surface during running, the content of BR in 100% by mass of the rubber component is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. There is no particular lower limit to the content, and it can be, for example, 1% by mass or more, 3% by mass or more, 5% by mass or more, or 10% by mass or more.

[0126] (Other rubber components) The rubber component may contain other rubber components besides diene rubber, as long as the effects of the present disclosure are not affected. Examples of other rubber components include crosslinkable rubber components commonly used in the tire industry, such as butyl rubber (IIR), halogenated butyl rubber, ethylene propylene rubber, polynorbornene rubber, silicone rubber, chlorinated polyethylene rubber, fluororubber (FKM), acrylic rubber (ACM), and hydrin rubber. These other rubber components may be used alone or in combination of two or more.

[0127] The polymer content in the rubber composition constituting the first layer 6 is preferably 40% by mass or less, more preferably 39% by mass or less, even more preferably 38% by mass or less, and particularly preferably 37% by mass or less. The polymer content in the rubber composition constituting the first layer 6 is preferably greater than the polymer content in the rubber composition constituting the second layer 7. By ensuring that the polymer content in the rubber composition constituting the first layer 6 falls within the above range and that the polymer content in the rubber composition constituting the first layer 6 is greater than the polymer content in the rubber composition constituting the second layer 7, it is believed that transmission of vibration through the polymer within the first layer 6 can be suppressed while facilitating transmission of force from the polymer chains in the second layer 7 to the first rubber layer. The lower limit of the polymer content in the rubber compositions constituting the first layer 6 and the second layer 7 is not particularly limited, but is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, and particularly preferably 25% by mass or more.

[0128] <Filler> The rubber composition according to the present disclosure preferably uses a filler containing carbon black and / or silica. A rubber composition constituting a rubber layer that is intended to come into contact with the road surface during driving preferably contains silica as a filler, more preferably carbon black and silica. A rubber composition constituting a rubber layer that is not intended to come into contact with the road surface during driving preferably contains carbon black as a filler.

[0129] (carbon black) The carbon black is not particularly limited, and can be, for example, one commonly used in the tire industry, such as GPF, FEF, HAF, ISAF, SAF, etc. These carbon blacks may be used alone or in combination of two or more.

[0130] The nitrogen adsorption specific surface area (N2SA) of carbon black is 10m from the viewpoint of reinforcement. 2 / g or more is preferable, and 30m 2 / g or more is more preferable, and 50m 2 / g or more is more preferable. From the viewpoint of fuel economy and processability, 200m 2 / g or less is preferable, and 150m 2 / g or less is more preferable, and 120m 2 The N2SA of carbon black is a value measured in accordance with JIS K 6217-2 "Fundamental properties of carbon black for rubber - Part 2: Determination of specific surface area - Nitrogen adsorption method - Single point method."

[0131] When the rubber composition constituting the rubber layer intended to come into contact with the road surface during running contains carbon black, the content of carbon black per 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more from the viewpoints of abrasion resistance and wet grip performance, and is preferably 50 parts by mass or less, more preferably 35 parts by mass or less, even more preferably 20 parts by mass or less, and particularly preferably 10 parts by mass or less from the viewpoint of fuel economy.

[0132] When the rubber composition constituting the rubber layer that is not intended to come into contact with the road surface during running contains carbon black, the content of carbon black per 100 parts by mass of the rubber component is preferably 20 parts by mass or more, more preferably 25 parts by mass or more, and even more preferably 30 parts by mass or more, and is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, and even more preferably 60 parts by mass or less.

[0133] (silica) The silica is not particularly limited, and can be, for example, silica prepared by a dry method (anhydrous silica) or silica prepared by a wet method (hydrated silica), which are commonly used in the tire industry. Among them, hydrated silica prepared by a wet method is preferred because it contains a large number of silanol groups. These silicas can be used alone or in combination of two or more.

[0134] The nitrogen adsorption specific surface area (N2SA) of silica is 120m from the viewpoint of fuel efficiency and wear resistance. 2 / g or more is preferable, and 150m 2 / g or more is more preferable, and 170m 2 / g or more is more preferable. From the viewpoint of fuel efficiency and processability, 2 / g or less is preferable, and 300m 2 / g or less is more preferable, and 250m 2 / g or less is more preferable. In this specification, the N2SA of silica is a value measured by the BET method in accordance with ASTM D3037-93.

[0135] When the rubber composition constituting the rubber layer intended to come into contact with the road surface during driving contains silica, the content of silica per 100 parts by mass of the rubber component is preferably 40 parts by mass or more, more preferably 50 parts by mass or more, even more preferably 60 parts by mass or more, and particularly preferably 70 parts by mass or more, from the viewpoint of wet grip performance. Furthermore, from the viewpoint of abrasion resistance, the content of silica is preferably 130 parts by mass or less, more preferably 120 parts by mass or less, and even more preferably 110 parts by mass or less. The content of silica per 100 parts by mass of the rubber component in the rubber composition constituting the rubber layer not intended to come into contact with the road surface during driving is not particularly limited.

[0136] The total content of silica and carbon black per 100 parts by mass of the rubber component is preferably 40 parts by mass or more, more preferably 50 parts by mass or more, even more preferably 60 parts by mass or more, and particularly preferably 70 parts by mass or more, from the viewpoint of abrasion resistance, and is preferably 160 parts by mass or less, more preferably 140 parts by mass or less, and even more preferably 120 parts by mass or less, from the viewpoint of fuel economy and elongation at break.

[0137] The rubber composition constituting the first layer 6 and the second layer 7 preferably contains a filler containing silica. The silica content in the filler is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, still more preferably 80% by mass or more, even more preferably 85% by mass or more, and particularly preferably 90% by mass or more. By setting the silica content in the filler within the above range, the loss tangent tanδ of the rubber composition can be reduced, and the phase difference from input to response can be reduced, which is thought to facilitate smooth acceleration at corner exits.

[0138] From the viewpoint of balancing fuel economy, wet grip performance, and abrasion resistance, the rubber composition constituting the first layer 6 and the second layer 7 preferably contains more silica than carbon black per 100 parts by mass of the rubber component. The proportion of silica relative to the total content of silica and carbon black in the first layer 6 and the second layer 7 is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 85% by mass or more, and particularly preferably 90% by mass or more. There are no particular restrictions on the proportions of silica and carbon black in the rubber composition constituting the third layer 8.

[0139] (Other fillers) As the filler, in addition to carbon black and silica, other fillers may also be used. Such fillers are not particularly limited, and any filler commonly used in this field, such as aluminum hydroxide, alumina (aluminum oxide), calcium carbonate, magnesium sulfate, talc, clay, etc., may be used. These fillers may be used alone or in combination of two or more.

[0140] (Silane coupling agent) Silica is preferably used in combination with a silane coupling agent.The silane coupling agent is not particularly limited, and any silane coupling agent that has been conventionally used in combination with silica in the tire industry can be used, for example, mercapto-based silane coupling agents such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane; sulfide-based silane coupling agents such as bis(3-triethoxysilylpropyl)disulfide, bis(3-triethoxysilylpropyl)tetrasulfide; 3-octanoylthio-1-propyltriethoxysilane, 3-hexanoylthio-1-propyltriethoxysilane, 3-octanoylthio-1-propyltrimethoxysilane; Examples of suitable silane coupling agents include thioester-based silane coupling agents such as silane; vinyl-based silane coupling agents such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based silane coupling agents such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and 3-(2-aminoethyl)aminopropyltriethoxysilane; glycidoxy-based silane coupling agents such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based silane coupling agents such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Among these, sulfide-based silane coupling agents and / or mercapto-based silane coupling agents are preferred. Examples of suitable silane coupling agents include those commercially available from Momentive, Inc. These silane coupling agents may be used alone or in combination.

[0141] When a silane coupling agent is contained, the content thereof per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, even more preferably 2.0 parts by mass or more, and particularly preferably 4.0 parts by mass or more, from the viewpoint of improving the dispersibility of silica, and is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 12 parts by mass or less, from the viewpoint of preventing a decrease in abrasion resistance.

[0142] The content of the silane coupling agent relative to 100 parts by mass of silica is preferably 1.0 part by mass or more, more preferably 3.0 parts by mass or more, and even more preferably 5.0 parts by mass or more, from the viewpoint of improving the dispersibility of silica. From the viewpoint of cost and processability, the content is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 12 parts by mass or less.

[0143] <Other compounding agents> In addition to the above components, the rubber composition according to the present disclosure may appropriately contain compounding agents conventionally commonly used in the tire industry, such as softeners, waxes, processing aids, stearic acid, zinc oxide, antioxidants, vulcanizing agents, and vulcanization accelerators.

[0144] (softener) The rubber composition according to the present disclosure preferably contains a softener, such as a resin component, oil, or liquid rubber.

[0145] The resin component is not particularly limited, but examples thereof include hydrocarbon resins commonly used in the tire industry, such as petroleum resins, terpene resins, rosin resins, and phenolic resins. These resin components may be used alone or in combination of two or more. At least one of the rubber composition constituting the first layer 6 and the rubber composition constituting the second layer 7 preferably contains a hydrocarbon resin, and more preferably contains an aromatic petroleum resin.

[0146] In this specification, "aromatic petroleum resin" refers to a resin obtained by polymerizing a C9 fraction, and may be a hydrogenated or modified version of the C9 fraction. Examples of C9 fractions include petroleum fractions having 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, indene, and methylindene. Specific examples of aromatic petroleum resins include: Coumarone-indene resin, coumarone resin, indene resin, and aromatic vinyl resin are preferably used. As the aromatic vinyl resin, a homopolymer of α-methylstyrene or styrene or a copolymer of α-methylstyrene and styrene is preferred, and a copolymer of α-methylstyrene and styrene is more preferred, because they are economical, easy to process, and have excellent heat generation properties. As the aromatic vinyl resin, for example, commercially available products from Kraton Corporation, Eastman Chemical Company, etc. can be used.

[0147] When a resin component is contained, the content thereof per 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more. The content of the resin component is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, even more preferably 40 parts by mass or less, and particularly preferably 30 parts by mass or less.

[0148] Examples of oils include process oil, vegetable oils, and animal fats. Examples of the process oil include paraffinic process oil, naphthenic process oil, and aromatic process oil. Furthermore, as an environmental measure, process oil with a low content of polycyclic aromatic compounds (PCA) can also be used. Examples of the low-PCA process oil include mild extract solvates (MES), treated distillate aromatic extracts (TDAE), and heavy naphthenic oil.

[0149] When oil is contained, the content per 100 parts by mass of the rubber component is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 15 parts by mass or more, and particularly preferably 20 parts by mass or more, from the viewpoint of processability. Also, from the viewpoint of abrasion resistance, the content is preferably 120 parts by mass or less, more preferably 100 parts by mass or less, and even more preferably 80 parts by mass or less. In this specification, the oil content includes the amount of oil contained in the oil-extended rubber.

[0150] The liquid rubber is not particularly limited as long as it is a polymer that is in a liquid state at room temperature (25°C), and examples thereof include liquid butadiene rubber (liquid BR), liquid styrene butadiene rubber (liquid SBR), liquid isoprene rubber (liquid IR), liquid styrene isoprene rubber (liquid SIR), liquid farnesene rubber, etc. These liquid rubbers may be used alone or in combination of two or more.

[0151] When a liquid rubber is contained, the content thereof per 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 2 parts by mass or more, even more preferably 3 parts by mass or more, and particularly preferably 5 parts by mass or more. The content of the liquid rubber is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 20 parts by mass or less.

[0152] When the rubber composition constituting the rubber layer intended to come into contact with the road surface during running contains a softener, the content (total amount of all softeners when multiple softeners are used) per 100 parts by mass of the rubber component is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 15 parts by mass or more, and particularly preferably 20 parts by mass or more. The content of the softener is preferably 120 parts by mass or less, more preferably 100 parts by mass or less, even more preferably 90 parts by mass or less, and particularly preferably 80 parts by mass or less.

[0153] When the rubber composition constituting the rubber layer that is not intended to come into contact with the road surface during driving contains a softener, the content (total amount of all softeners when multiple softeners are used) per 100 parts by mass of the rubber component is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, even more preferably 20 parts by mass or less, and particularly preferably 15 parts by mass or less.

[0154] When wax is contained, the content per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more from the viewpoint of weather resistance of the rubber, and is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less from the viewpoint of preventing whitening of the tire due to bloom.

[0155] Examples of processing aids include fatty acid metal salts, fatty acid amides, amide esters, silica surfactants, fatty acid esters, mixtures of fatty acid metal salts and amide esters, and mixtures of fatty acid metal salts and fatty acid amides. These processing aids may be used alone or in combination of two or more. Examples of processing aids that can be used include those commercially available from Schill + Seilacher, Performance Additives, etc.

[0156] When a processing aid is contained, the content thereof per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and even more preferably 1.5 parts by mass or more, from the viewpoint of improving processability, and is preferably 10 parts by mass or less, more preferably 8.0 parts by mass or less, from the viewpoint of abrasion resistance and breaking strength.

[0157] The antioxidant is not particularly limited, but examples thereof include amine-based, quinoline-based, quinone-based, phenol-based, and imidazole-based compounds, as well as metal carbamates. Preferred are phenylenediamine-based antioxidants such as N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N-isopropyl-N'-phenyl-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine, N,N'-di-2-naphthyl-p-phenylenediamine, and N-cyclohexyl-N'-phenyl-p-phenylenediamine, and quinoline-based antioxidants such as 2,2,4-trimethyl-1,2-dihydroquinoline polymer and 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline. These antioxidants may be used alone or in combination of two or more.

[0158] When an antioxidant is contained, the content per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more, from the viewpoint of ozone crack resistance of the rubber, and is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less, from the viewpoint of abrasion resistance and wet grip performance.

[0159] When stearic acid is contained, the content per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and even more preferably 1.5 parts by mass or more from the viewpoint of processability, and is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less from the viewpoint of vulcanization rate.

[0160] When zinc oxide is contained, the content per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more from the viewpoint of processability, and is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less from the viewpoint of abrasion resistance.

[0161] As the vulcanizing agent, sulfur is preferably used, and examples of sulfur that can be used include powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersible sulfur.

[0162] When sulfur is contained as a vulcanizing agent, the content per 100 parts by mass of the rubber component is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and even more preferably 0.5 parts by mass or more, from the viewpoint of ensuring a sufficient vulcanization reaction. Furthermore, from the viewpoint of preventing deterioration, the content is preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, even more preferably 3.0 parts by mass or less, and particularly preferably 2.5 parts by mass or less. When oil-containing sulfur is used as the vulcanizing agent, the content of the vulcanizing agent is the total content of pure sulfur contained in the oil-containing sulfur.

[0163] Examples of vulcanizing agents other than sulfur include alkylphenol-sulfur chloride condensate, sodium 1,6-hexamethylene-dithiosulfate dihydrate, 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane, etc. These vulcanizing agents other than sulfur can be commercially available from Taoka Chemical Co., Ltd., Lanxess K.K., Flexis, etc.

[0164] Examples of vulcanization accelerators include sulfenamide-based, thiazole-based, thiuram-based, thiourea-based, guanidine-based, dithiocarbamic acid-based, aldehyde-amine-based or aldehyde-ammonia-based, imidazoline-based, and xanthate-based vulcanization accelerators. These vulcanization accelerators may be used alone or in combination of two or more. Among them, one or more vulcanization accelerators selected from the group consisting of sulfenamide-based, guanidine-based, and thiazole-based vulcanization accelerators are preferred, and sulfenamide-based vulcanization accelerators are more preferred.

[0165] Examples of sulfenamide vulcanization accelerators include N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N,N-dicyclohexyl-2-benzothiazolylsulfenamide (DCBS), etc. Among these, N-cyclohexyl-2-benzothiazolylsulfenamide (CBS) is preferred.

[0166] Examples of guanidine vulcanization accelerators include 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salt of dicatechol borate, 1,3-di-o-cumenylguanidine, 1,3-di-o-biphenylguanidine, 1,3-di-o-cumenyl-2-propionylguanidine, etc. Among these, 1,3-diphenylguanidine (DPG) is preferred.

[0167] Examples of the thiazole vulcanization accelerator include 2-mercaptobenzothiazole, cyclohexylamine salt of 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, etc. Among these, 2-mercaptobenzothiazole is preferred.

[0168] When a vulcanization accelerator is contained, the content (total amount when multiple vulcanization accelerators are used) per 100 parts by mass of the rubber component is preferably 1.0 part by mass or more, more preferably 2.0 parts by mass or more, and even more preferably 2.5 parts by mass or more. The content is preferably 8.0 parts by mass or less, more preferably 7.0 parts by mass or less, and even more preferably 6.0 parts by mass or less. By keeping the content of the vulcanization accelerator within the above range, breaking strength and elongation tend to be ensured.

[0169] <Manufacturing> The rubber composition according to the present disclosure can be produced by a known method, for example, by kneading the above-described components using a rubber kneading device such as an open roll or an internal kneader (such as a Banbury mixer or kneader).

[0170] The kneading step includes, for example, a base kneading step in which compounding ingredients and additives other than the vulcanizing agent and vulcanization accelerator are kneaded, and a final kneading (F kneading) step in which the vulcanizing agent and vulcanization accelerator are added to the kneaded product obtained in the base kneading step and kneaded. Furthermore, the base kneading step can be divided into multiple steps as desired.

[0171] The kneading conditions are not particularly limited, but examples include a method in which the base kneading step involves kneading for 3 to 10 minutes at a discharge temperature of 150 to 170°C, and a method in which the final kneading step involves kneading for 1 to 5 minutes at 70 to 110°C. The vulcanization conditions are not particularly limited, but examples include a method in which vulcanization is carried out for 10 to 30 minutes at 150 to 200°C.

[0172] A tire having a tread including a first layer 6 and a second layer 7 can be manufactured by a conventional method using the corresponding rubber compositions. That is, the unvulcanized rubber compositions corresponding to the respective rubber layers obtained by the above-described method are extruded to match the shape of each rubber layer using an extruder equipped with a predetermined shape of die, and then bonded together with other tire components on a tire building machine and molded by a conventional method to form an unvulcanized tire. The unvulcanized tire can then be heated and pressurized in a vulcanizer to manufacture a tire. The vulcanization conditions are not particularly limited, and examples include a method of vulcanizing at 150 to 200°C for 10 to 30 minutes.

[0173] <Application> The tire of the present disclosure can be suitably used as a passenger car tire, a truck / bus tire, a motorcycle tire, or a racing tire, and is particularly preferably used as a passenger car tire. Passenger car tires are tires designed to be mounted on four-wheeled vehicles and have a maximum load capacity of 1000 kg or less. The tire of the present disclosure can also be used as an all-season tire, a summer tire, or a winter tire such as a studless tire. [Example]

[0174] The present disclosure will be described based on examples, but the present disclosure is not limited to only the examples.

[0175] <Production of rubber composition and tire> The various chemicals used in the examples and comparative examples are listed below. NR:TSR20 SBR1: Modified S-SBR produced in Production Example 1 described below (styrene content: 30% by mass, vinyl bond content: 52% by mole, Mw: 250,000, non-oil-extended product) SBR2: Modified S-SBR produced in Production Example 2 described below (styrene content: 40% by mass, vinyl content: 25% by mole, Mw: 1,000,000, non-oil-extended product). SBR3: Modified S-SBR produced in Production Example 3 described below (styrene content: 25% by mass, vinyl content: 25% by mole, Mw: 1,000,000, non-oil-extended). BR: UBEPOL BR (registered trademark) 150B (cis content: 97 mol%, Mw: 440,000) manufactured by Ube Industries, Ltd. Carbon black: Show Black N220 (N2SA: 111m) manufactured by Cabot Japan Co., Ltd. 2 / g) Silica: Ultrasil VN3 (N2SA: 175 ml) manufactured by Evonik Degussa 2 / g) Silane coupling agent: Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa Oil: H&R VivaTec 400 (TDAE oil) Resin component: Kraton Sylvatraxx 4401 (copolymer of α-methylstyrene and styrene) Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Anti-aging agent: Antigen 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd. Stearic acid: Camellia stearic acid beads manufactured by NOF Corporation Wax: Ozoace 0355 by Nippon Seiro Co., Ltd. Sulfur: HK-200-5 (powdered sulfur containing 5% oil) manufactured by Hosoi Chemical Industry Co., Ltd. Vulcanization accelerator 1: Noccela CZ (N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 2: Noccelaer D (1,3-diphenylguanidine (DPG)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0176] Production Example 1: Synthesis of SBR1 Cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene were charged into a nitrogen-purged autoclave reactor. After adjusting the temperature of the reactor contents to 20°C, n-butyllithium was added to initiate polymerization. Polymerization was carried out under adiabatic conditions, with a maximum temperature of 85°C. When the polymerization conversion reached 99%, 1,3-butadiene was added, and the polymerization was continued for an additional 5 minutes. N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane was then added as a modifier, and the reaction was continued. After the polymerization reaction was completed, 2,6-di-tert-butyl-p-cresol was added. The solvent was then removed by steam stripping, and the mixture was dried on a heated roll heated to 110°C to obtain SBR1.

[0177] Production Example 2: Synthesis of SBR2 Cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene were charged into a nitrogen-purged autoclave reactor. The ratio of styrene to 1,3-butadiene was adjusted so that the styrene content was 40% by mass. After adjusting the temperature of the reactor contents to 20°C, n-butyllithium was added to initiate polymerization. Polymerization was carried out under adiabatic conditions, reaching a maximum temperature of 80°C. When the polymerization conversion reached 99%, additional 1,3-butadiene was added, and the polymerization was continued for an additional 5 minutes. N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane was then added as a modifier, and the reaction was continued. After the polymerization reaction was completed, 2,6-di-tert-butyl-p-cresol was added. The solvent was then removed by steam stripping, and the mixture was dried on a heated roll heated to 110°C to obtain SBR2.

[0178] Production Example 3: Synthesis of SBR3 SBR3 was obtained in the same manner as in Production Example 2, except that the ratio of styrene to 1,3-butadiene was adjusted so that the styrene content was 25% by mass.

[0179] <Manufacturing low-density components> (Low-density material 1 (sound-damping body)) A polyurethane sponge containing an ether-based polyurethane sponge having the shape shown in Fig. 1 was used as the noise damper 39. The volume of the noise damper was 15% of the total volume of the tire cavity, and the density was 2.7 x 10 -2 g / cm 3 , Tg is -50°C.

[0180] Examples and Comparative Examples According to the formulation shown in Table 1, the chemicals other than sulfur and the vulcanization accelerator were mixed in a 1.7 L closed-type Banbury mixer for 1 to 10 minutes until the discharge temperature reached 150 to 160°C, yielding a kneaded mixture. Next, sulfur and the vulcanization accelerator were added to the resulting mixture using a two-screw open roll mill, and the mixture was mixed for 4 minutes until the temperature reached 105°C, yielding an unvulcanized rubber composition. The resulting unvulcanized rubber composition was molded to match the shapes of the first, second, third, and fourth layers of the tread, and then bonded together with other tire components to produce an unvulcanized tire. The tire was then vulcanized at 170°C to obtain the test tires listed in Tables 1 and 2. The maximum groove depth H1 of the circumferential grooves was 8.0 mm.

[0181] <Measurement of polymer amount> Each vulcanized rubber specimen cut from the rubber layer of the tread of each test tire was immersed in acetone for 24 hours to extract acetone-soluble components in accordance with JIS K 6229:2015. The specimens were then heated and dried to remove the solvent, and the mass of each vulcanized rubber specimen after acetone-soluble component extraction was measured. Next, the vulcanized rubber specimens were pyrolyzed in a nitrogen stream by thermogravimetry in accordance with JIS K 6226-1:2003, increasing the temperature from room temperature to 750°C at a rate of 10°C / min. The mass of the specimen after pyrolysis was measured. The "polymer content (mass%)" in each rubber composition was calculated by subtracting the mass of the vulcanized rubber specimen after acetone-soluble component extraction from the mass of the specimen after pyrolysis, where the mass of the vulcanized rubber specimen before acetone extraction was taken as 100% by mass.

[0182] <Measurement of loss tangent tanδ, complex modulus of elasticity E*, and glass transition temperature (Tg)> Each test tire was cut from the rubber layer in the tread of a test tire, measuring 20 mm in length, 4 mm in width, and 1 mm in thickness, with the long side aligned in the tire circumferential direction. The loss tangent (tanδ) and complex modulus (E*) of each test tire were measured using a GABO Iplexer series at a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain of 1%. The temperature distribution curve of tanδ was measured at a frequency of 10 Hz, an initial strain of 10%, an amplitude of ±0.5%, and a heating rate of 2°C / min. The temperature corresponding to the largest tanδ value in the temperature distribution curve (tanδ peak temperature) was taken as the glass transition temperature (Tg). The thickness direction of the sample was the radial direction of the tire.

[0183] <Measuring rubber hardness (Hs)> The Shore hardness (Hs) of each rubber test piece was measured at a temperature of 23° C. using a durometer type A in accordance with JIS K 6253-3:2012. Each rubber test piece was cut out from inside the rubber layer of the tread portion of each test tire.

[0184] <Tensile test> A 1mm thick dumbbell-shaped No. 7 test piece was cut from inside the rubber layer of the tread portion of each test tire so that the tensile direction was the tire circumferential direction, and a tensile test was carried out in accordance with JIS K 6251:2017 "Vulcanized rubber and thermoplastic rubber - Determination of tensile test properties" at a temperature of 23°C and a tensile speed of 3.3mm / sec to measure the modulus (MPa) at 100% elongation. The thickness direction of the sample was the radial direction of the tire.

[0185] <Handling stability> Each test tire was mounted on four wheels of a 2000cc FF passenger car, and the car was driven on a test course with a dry asphalt surface. The test drivers evaluated the handling characteristics based on the feeling they got when accelerating at the corner exit. The evaluation was performed using an integer value from 1 to 10, and the total score of the 10 test drivers was calculated based on the evaluation criteria where the higher the score, the better the handling characteristics. Comparative Example 1 and Comparative Example 7 The total score of each The total score was converted to a standard value (100), and the evaluation results of each test tire were expressed as an index proportional to the total score.

[0186] <Noise performance> Each test tire when new and each test tire after wear were mounted on four wheels of a 2000cc FF passenger car, and the car was driven on a test course with a dry asphalt surface. The noise felt by the test drivers inside the car when driving at 120km / h was evaluated based on their own feelings. The evaluation was performed using an integer value from 1 to 10, and the higher the score, the better the noise performance. The total score of the 10 test drivers was calculated based on the evaluation criteria. Comparative Example 1 and Comparative Example 7 The total score of each The total score was converted to a standard value (100), and the evaluation results of each test tire were expressed as an index proportional to the total score.

[0187] In addition, the overall performance of handling stability performance and noise performance (handling stability performance index and noise Suppression of deterioration The performance target is a value of over 200 for the sum of the indexes.

[0188] [Table 1]

[0189] [Table 2]

[0190] [Table 3]

[0191] The results in Tables 1 to 3 show that the tires of the present disclosure, which have two or more rubber layers laminated in the tread portion of the tire and have the complex modulus of elasticity of the rubber layers and the groove depth of the circumferential grooves set in a predetermined relationship, have improved overall performance in terms of steering stability and noise performance during high-speed driving.

[0192] <Embodiment> Examples of embodiments of the present disclosure are provided below.

[0193] [1] A tire having a tread portion including at least a first rubber layer constituting a tread surface and a second rubber layer adjacent to the first rubber layer on the radially inner side thereof, wherein the tread portion has two or more circumferential grooves extending continuously in the tire circumferential direction, a pair of shoulder land portions separated by the circumferential grooves and the ground contact edge, and a center land portion located between the pair of shoulder land portions, the first rubber layer and the second rubber layer are made of a rubber composition containing a rubber component, the ratio (H2 / H1) of the distance H2 (mm) from the outermost surface of the tread portion to the groove depth H1 (mm) of the deepest part of the circumferential groove is 0.40 to 0.90, and the complex modulus (MPa) of the first rubber layer at 30°C is E* T , the complex modulus (MPa) of the second rubber layer at 30 ° C. is E* B Then, E* B is E* T and the E* for the H2 / H1 T The ratio (E* T / (H2 / H1)) is 6.0 or more. [2] The tire according to [1] above, wherein the rubber compositions constituting the first rubber layer and the second rubber layer contain a filler containing silica, and the content of silica in the filler is 50% by mass or more. [3] The tire according to [1] or [2] above, further comprising a third rubber layer adjacent to the second rubber layer on the radially inner side of the tire. [4] The tire according to any one of [1] to [3] above, wherein the tire inner circumferential surface of the tread portion is provided with one or more low-density members selected from the group consisting of a sealant layer, a noise-deadening material, and a three-dimensional mesh structure. [5] The tire according to any one of the above [1] to [4], wherein the polymer amount in the rubber composition constituting the first rubber layer is 40 mass% or less, and the polymer amount in the rubber composition constituting the first rubber layer is greater than the polymer amount in the rubber composition constituting the second rubber layer. [6] The tire according to any one of [1] to [5] above, having a tire section width of 205 mm or more. [7] The tire according to any one of the above [1] to [6], wherein the land area ratio in the contact patch is 60 to 80%. [8] The tire according to any one of [1] to [7] above, wherein the land area ratio in the contact patch is asymmetric around the tire equatorial plane. [9] A tire described in any one of [1] to [8] above, in which the circumferential groove is not present on the tire equatorial plane, and the distance from the tire equatorial plane to the groove edge of the circumferential groove that is closest in the vehicle inner direction is different from the distance from the tire equatorial plane to the groove edge of the circumferential groove that is closest in the vehicle outer direction.

[10] The tire according to any one of the above [1] to [9], wherein the groove area ratio in the shoulder land portion is larger than the groove area ratio in the center land portion.

[11] The tire according to any one of the above [1] to

[10] , wherein the width direction length of at least one of the land portions gradually increases from the outer side toward the inner side in the tire radial direction.

[12] The groove width on the tread surface of the circumferential groove positioned at the outermost side when mounted on a vehicle is L0, and the groove width at the 95% position of the deepest part of the groove bottom of the circumferential groove positioned at the outermost side when mounted on a vehicle is L1. Groove Width L 95 When L 95 The tire according to any one of the above [1] to

[11] , wherein / L0 is 0.20 to 0.80.

[13] The tire according to any one of the above [1] to

[12] , wherein at least one of the rubber composition constituting the first rubber layer and the rubber composition constituting the second rubber layer contains a hydrocarbon resin.

[14] Complex modulus E* of the first rubber layer at 30 ° C. T The tire according to any one of the above [1] to

[13] , wherein the compressive strength is 4.0 MPa or more.

[15] The tire according to any one of the above [1] to

[14] , wherein the second rubber layer has a tan δ at 30° C. of 0.25 or less.

[16] The tire according to any one of the above [1] to

[15] , wherein the first rubber layer has a glass transition temperature of −25° C. or higher.

[17] The tire according to any one of the above [1] to

[16] , wherein the second rubber layer has a Shore hardness (Hs) of 50 to 80, measured in accordance with JIS K 6253-3:2012 using a durometer type A at a temperature of 23°C.

[18] The tire according to any one of the above [1] to

[17] , wherein the modulus of the second rubber layer at 100% stretch is greater than the modulus of the first rubber layer at 100% stretch. [Explanation of symbols]

[0194] 1 Tread section 2 Land 4 Extension of land area 5 Extension line of the deepest part of the bottom of the circumferential groove 6 First layer 7 Second layer 8 Third layer 9. Outermost extension of the second layer 10 Tread surface 11, 12, 13, 14 Circumferential groove 15 Circumferential groove wall 16 Outer shoulder land area 17 Inner shoulder land area 18 Outer Center Land 19 Inner Center Land 20 Center Land Section 21 Shoulder groove 22 Shoulder sipes 23 Center sipe 31 Bead core 32 Sidewall 33 Bead section 34 Carcass 35 Belt 36 bands 37 Groove 38 rims 39 Sound damping body 61 Edge Band 62 Full Band C Tire equatorial plane CL Tire centerline To outer tread edge Ti inner tread edge W Tire width direction H1 circumferential groove bottom

Claims

1. A tire having a tread portion including at least a first rubber layer constituting a tread surface and a second rubber layer adjacent to the first rubber layer on the radially inner side of the tire, the tread portion has two or more circumferential grooves extending continuously in the tire circumferential direction, a pair of shoulder land portions separated by the circumferential grooves and the ground contact edge, and a center land portion located between the pair of shoulder land portions, The land area ratio within the contact patch is 60 to 80%. The land area ratio in the contact patch is asymmetric around the tire equatorial plane, the first rubber layer and the second rubber layer are made of a rubber composition containing a rubber component, The groove depth H of the deepest part of the circumferential groove 1 The distance H (mm) from the outermost surface of the tread portion to the outermost part of the second rubber layer 2 (mm) ratio (H 2 / H 1 ) is 0.40 to 0.90, The complex modulus (MPa) of the first rubber layer at 30°C is E* T The complex modulus (MPa) of the second rubber layer at 30°C is E* B When E* B is E* T and the H 2 / H 1 The E* T The ratio (E* T / (H 2 / H 1 )) is 6.0 or more, the glass transition temperature of the first rubber layer is −25° C. or higher, The tire, wherein the second rubber layer has a Shore hardness (Hs) of 61 to 80 as measured in accordance with JIS K 6253-3:2012 using a durometer type A at a temperature of 23°C.

2. A tire having a tread portion including at least a first rubber layer constituting a tread surface and a second rubber layer adjacent to the first rubber layer on the radially inner side of the tire, the tread portion has two or more circumferential grooves extending continuously in the tire circumferential direction, a pair of shoulder land portions separated by the circumferential grooves and the ground contact edge, and a center land portion located between the pair of shoulder land portions, The land area ratio within the contact patch is 60 to 80%. the first rubber layer and the second rubber layer are made of a rubber composition containing a rubber component, The groove depth H of the deepest part of the circumferential groove 1 The distance H (mm) from the outermost surface of the tread portion to the outermost part of the second rubber layer 2 (mm) ratio (H 2 / H 1 ) is 0.40 to 0.90, The complex modulus (MPa) of the first rubber layer at 30°C is E* T The complex modulus (MPa) of the second rubber layer at 30°C is E* B When E* B is E* T and the H 2 / H 1 The E* T The ratio (E* T / (H 2 / H 1 )) is 6.0 or more, the glass transition temperature of the first rubber layer is −25° C. or higher, the first rubber layer has a Shore hardness (Hs) of 50 to 61, measured in accordance with JIS K 6253-3:2012 using a durometer type A at a temperature of 23°C; The tire, wherein the second rubber layer has a Shore hardness (Hs) of 50 to 80 as measured in accordance with JIS K 6253-3:2012 using a durometer type A at a temperature of 23°C.

3. A tire having a tread portion including at least a first rubber layer constituting a tread surface, a second rubber layer adjacent to the first rubber layer on the radially inner side of the tire, and a third rubber layer adjacent to the second rubber layer on the radially inner side of the tire, the tread portion has two or more circumferential grooves extending continuously in the tire circumferential direction, a pair of shoulder land portions separated by the circumferential grooves and the ground contact edge, and a center land portion located between the pair of shoulder land portions, the first rubber layer, the second rubber layer, and the third rubber layer are each made of a rubber composition containing a rubber component, The groove depth H of the deepest part of the circumferential groove 1 The distance H (mm) from the outermost surface of the tread portion to the outermost part of the second rubber layer 2 (mm) ratio (H 2 / H 1 ) is 0.40 to 0.90, The complex modulus (MPa) of the first rubber layer at 30°C is E* T The complex modulus (MPa) of the second rubber layer at 30°C is E* B When E* B is E* T and the H 2 / H 1 The E* T The ratio (E* T / (H 2 / H 1 )) is 6.0 or more, the glass transition temperature of the first rubber layer is −25° C. or higher, the second rubber layer has a tan δ at 30°C of 0.12 or more and 0.25 or less; The tire, wherein the second rubber layer has a Shore hardness (Hs) of 50 to 80 as measured in accordance with JIS K 6253-3:2012 using a durometer type A at a temperature of 23°C.

4. A tire having a tread portion including at least a first rubber layer constituting a tread surface and a second rubber layer adjacent to the first rubber layer on the radially inner side of the tire, the tread portion has two or more circumferential grooves extending continuously in the tire circumferential direction, a pair of shoulder land portions separated by the circumferential grooves and the ground contact edge, and a center land portion located between the pair of shoulder land portions, The tire section width is 205 mm or more, the first rubber layer and the second rubber layer are made of a rubber composition containing a rubber component, the rubber component constituting the first rubber layer contains a styrene-butadiene rubber, and the content of an isoprene-based rubber in 100% by mass of the rubber component is 30% by mass or less; the rubber compositions constituting the first rubber layer and the second rubber layer contain a filler containing silica, and the content of silica in the filler is 50% by mass or more; The groove depth H of the deepest part of the circumferential groove 1 The distance H (mm) from the outermost surface of the tread portion to the outermost part of the second rubber layer 2 (mm) ratio (H 2 / H 1 ) is 0.40 to 0.90, a modulus of the second rubber layer at 100% elongation is greater than a modulus of the first rubber layer at 100% elongation, The complex modulus (MPa) of the first rubber layer at 30°C is E* T The complex modulus (MPa) of the second rubber layer at 30°C is E* B When E* B is E* T and the H 2 / H 1 The E* T The ratio (E* T / (H 2 / H 1 )) is 6.0 or more.

5. A tire having a tread portion including at least a first rubber layer constituting a tread surface and a second rubber layer adjacent to the first rubber layer on the radially inner side of the tire, the tread portion has two or more circumferential grooves extending continuously in the tire circumferential direction, a pair of shoulder land portions separated by the circumferential grooves and the ground contact edge, and a center land portion located between the pair of shoulder land portions, The land area ratio within the contact patch is 60 to 80%. the first rubber layer and the second rubber layer are made of a rubber composition containing a rubber component, a rubber composition constituting the first rubber layer has an oil content of 20 parts by mass or more per 100 parts by mass of the rubber component; the rubber compositions constituting the first rubber layer and the second rubber layer contain a filler containing silica, and the content of silica in the filler is 50% by mass or more; The groove depth H of the deepest part of the circumferential groove 1 The distance H (mm) from the outermost surface of the tread portion to the outermost part of the second rubber layer 2 (mm) ratio (H 2 / H 1 ) is 0.40 to 0.90, a modulus of the second rubber layer at 100% elongation is greater than a modulus of the first rubber layer at 100% elongation, The complex modulus (MPa) of the first rubber layer at 30°C is E* T The complex modulus (MPa) of the second rubber layer at 30°C is E* B When E* B is E* T and the H 2 / H 1 The E* T The ratio (E* T / (H 2 / H 1 )) is 6.0 or more.

6. A tire having a tread portion including at least a first rubber layer constituting a tread surface, a second rubber layer adjacent to the first rubber layer on the radially inner side of the tire, and a third rubber layer adjacent to the second rubber layer on the radially inner side of the tire, the tread portion has two or more circumferential grooves extending continuously in the tire circumferential direction, a pair of shoulder land portions separated by the circumferential grooves and the ground contact edge, and a center land portion located between the pair of shoulder land portions, The land area ratio within the contact patch is 60 to 80%. the first rubber layer, the second rubber layer, and the third rubber layer are each made of a rubber composition containing a rubber component, The groove depth H of the deepest part of the circumferential groove 1 The distance H (mm) from the outermost surface of the tread portion to the outermost part of the second rubber layer 2 (mm) ratio (H 2 / H 1 ) is 0.40 to 0.90, The complex modulus (MPa) of the first rubber layer at 30°C is E* T The complex modulus (MPa) of the second rubber layer at 30°C is E* B When E* B is E* T and the H 2 / H 1 The E* T The ratio (E* T / (H 2 / H 1 )) is 6.0 or more, the glass transition temperature of the first rubber layer is −25° C. or higher, The tire, wherein the first rubber layer has a Shore hardness (Hs) of 50 to 61 as measured in accordance with JIS K 6253-3:2012 using a durometer type A at a temperature of 23°C.

7. The tire according to claim 3 or 6, wherein the content of the isoprene-based rubber in 100% by mass of the rubber component constituting the third rubber layer is 75% by mass or more.

8. 5. The tire according to claim 3, wherein the land area ratio within the contact patch is 60 to 80%.

9. The tire according to any one of claims 3 to 6, wherein the land area ratio in the contact patch is asymmetric about the tire equatorial plane.

10. The tire according to claim 4 or 5, wherein the second rubber layer has a Shore hardness (Hs) of 50 to 80 as measured in accordance with JIS K 6253-3:2012 using a durometer type A at a temperature of 23°C.

11. The tire according to any one of claims 1 to 10, further comprising one or more low-density members selected from the group consisting of a sealant layer, a noise-damping material, and a three-dimensional mesh structure, on an inner circumferential surface of the tire in the tread portion.

12. the polymer content in the rubber composition constituting the first rubber layer is 40% by mass or less, and The tire according to any one of claims 1 to 11, wherein a polymer amount in a rubber composition constituting the first rubber layer is greater than a polymer amount in a rubber composition constituting the second rubber layer.

13. The circumferential groove is not present on the tire equatorial plane, and The tire according to any one of claims 1 to 12, wherein a distance from the tire equatorial plane to a groove edge of the circumferential groove that is closest in a vehicle inner direction is different from a distance from the tire equatorial plane to a groove edge of the circumferential groove that is closest in a vehicle outer direction.

14. The tire according to any one of claims 1 to 13, wherein a groove area ratio in the shoulder land portion is greater than a groove area ratio in the center land portion.

15. The tire according to any one of claims 1 to 14, wherein a width direction length of at least one of the land portions gradually increases from the outer side toward the inner side in the tire radial direction.

16. The groove width on the tread surface of the circumferential groove located at the outermost side when mounted on a vehicle is L 0 The groove width at 95% of the deepest part of the groove bottom of the circumferential groove located at the outermost side when mounted on a vehicle is L 95 When this is done, L 95 / L 0 The tire according to any one of claims 1 to 15, wherein is 0.20 to 0.

80.

17. The tire according to any one of claims 1 to 16, wherein at least one of the rubber composition constituting the first rubber layer and the rubber composition constituting the second rubber layer contains a hydrocarbon resin.

18. Complex modulus E* of the first rubber layer at 30°C T The tire according to any one of claims 1 to 17, wherein the tensile strength is 4.0 MPa or more.

19. The tire according to any one of claims 1 to 18, wherein the first rubber layer has a glass transition temperature of -11°C or higher.

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