tire

Abstract

To provide a tire with improved peak grip performance.SOLUTION: In a tire which is provided with a tread part: the tread part is composed of a rubber composition comprising a rubber component and fillers; a total content of the fillers in the rubber composition based on 100 parts by mass of the rubber component is greater than 100 parts by mass; a glass transition temperature Tg2 (°C) of the rubber composition after acetone extraction is below -45°C; and when a land ratio in a grounding surface of the tread part is defined as R(%), Tg2 and R satisfy (10-1.25Tg2) / R>1.0.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This disclosure relates to tires. [Background technology]

[0002] Pneumatic tires, especially high-performance tires such as racing tires, are required to exhibit excellent grip performance (peak grip performance) even after the tire has warmed up after prolonged driving. Patent Document 1 discloses a rubber composition for tire treads that contains a specific carbon black and exhibits excellent grip performance from the initial stages of driving and peak grip performance. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2012-158662 [Overview of the project] [Problems that the invention aims to solve]

[0004] This disclosure aims to provide a tire with improved peak grip performance. [Means for solving the problem]

[0005] After thorough investigation, it was found that the above problem can be solved by a tire in which the total filler content of the rubber composition constituting the tread portion is more than 100 parts by mass per 100 parts by mass of rubber component, the glass transition temperature Tg2 (°C) of the rubber composition after acetone extraction is less than -45°C, and when R (%) is the land ratio at the contact surface of the tread portion, Tg2 and R satisfy a predetermined relationship.

[0006] In other words, the present disclosure relates to a tire having a tread portion, wherein the tread portion is composed of a rubber composition containing a rubber component and a filler, the rubber composition contains more than 100 parts by mass of filler per 100 parts by mass of rubber component, the glass transition temperature Tg2 (°C) of the rubber composition after acetone extraction is less than -45°C, and when the land ratio at the contact surface of the tread portion is R (%), Tg2 and R satisfy the following formula (1). (10-1.25Tg2) / R>1.00···(1) [Effects of the Invention]

[0007] According to this disclosure, a tire with improved peak grip performance is provided. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram of the contact surface of a tire when the tread is pressed against a flat surface. [Figure 2] This is a schematic diagram of the tire's contact surface, representing another embodiment. [Modes for carrying out the invention]

[0009] A tire according to one embodiment of the present disclosure is a tire having a tread portion, wherein the tread portion is composed of a rubber composition containing a rubber component and a filler, the rubber composition contains more than 100 parts by mass of filler per 100 parts by mass of rubber component, the glass transition temperature Tg2 (°C) of the rubber composition after acetone extraction is less than -45, and when the land ratio at the contact surface of the tread portion is R (%), Tg2 and R satisfy the following formula (1). (10-1.25Tg2) / R>1.00···(1)

[0010] When the land ratio on the grounding surface of the tread portion, the filler content, and the glass transition temperature Tg2 (°C) after acetone extraction of the rubber composition satisfy the above requirements, the obtained tire has improved peak grip performance. Although not intending to be bound by theory, the reason is considered as follows.

[0011] (1) Since the glass transition temperature Tg2 (°C) after acetone extraction is less than -45 °C, the polymer mobility is high even at low temperatures, so the rubber is easily deformed and the contact area with the road surface increases. (2) Since the total filler content exceeds 100 parts by mass with respect to 100 parts by mass of the rubber component, the heat generation property of the rubber composition constituting the tread portion increases, so the followability to the road surface also improves during high-temperature running after the middle stage of running. Furthermore, (3) by lowering the glass transition temperature Tg2 (°C) after acetone extraction as the land ratio on the grounding surface of the tread portion increases, good rigidity can be obtained together with the rubber mobility and heat generation property. And it is considered that the remarkable effect that the peak grip performance is improved is achieved by the cooperation of these (1) to (3).

[0012] The glass transition temperature Tg1 (°C) of the rubber composition before acetone extraction is preferably -15 °C or lower.

[0013] By lowering the glass transition temperature Tg1 (°C) before acetone extraction, the polymer mobility is high even at low temperatures, so it is considered that the rubber is easily deformed and the contact area with the road surface increases.

[0014] The sulfur content S (mass %) in the rubber component of the rubber composition is preferably 0.95 or less.

[0015] By lowering the sulfur content in the rubber component, it is considered that it is possible to prevent the polymer chains from being excessively restricted by vulcanization, easily obtain heat generation property, and easily improve the peak grip performance.

[0016] The rubber composition preferably further contains liquid rubber.

[0017] It is believed that including liquid rubber increases the tanδ of the rubber composition, improving the tackiness on the rubber surface and further enhancing peak grip performance.

[0018] The rubber composition preferably contains more than 5 parts by mass but less than 150 parts by mass of carbon black per 100 parts by mass of rubber component.

[0019] By incorporating carbon black into the rubber composition and setting the amount within the above range, it is believed that the heat generation properties of the rubber composition constituting the tread will be improved, and the peak grip performance will be further enhanced.

[0020] The rubber composition preferably contains silica with an average primary particle diameter of 18 nm or less.

[0021] It is believed that incorporating small-particle silica into the rubber composition will improve heat generation and further enhance peak grip performance.

[0022] The rubber hardness of the rubber composition is preferably greater than 62 and less than 75.

[0023] It is believed that having the rubber hardness of the rubber composition within the above range will result in good rigidity and further improve peak grip performance.

[0024] Preferably, the tanδ (0°C tanδ) of the rubber composition at 0°C is greater than 0.40.

[0025] It is believed that peak grip performance can be further improved by setting tanδ at 0°C within the aforementioned range.

[0026] Preferably, the tanδ (30°C tanδ) of the rubber composition at 30°C is greater than 0.20.

[0027] It is believed that peak grip performance can be further improved by setting tanδ at 30°C within the aforementioned range.

[0028] The complex modulus (E*) of the rubber composition at 30°C 30 ) is preferably less than 30 MPa.

[0029] By setting the complex modulus of the rubber composition at 30°C within the aforementioned range, the heat generation of the rubber composition constituting the tread portion is increased, which is thought to improve peak grip performance.

[0030] The product of tanδ at 100°C and R (tanδ at 100°C × R) of the rubber composition is preferably 5.0 or greater.

[0031] It is believed that a product of 100°C tanδ and land ratio R of 5.0 or higher allows for stable friction across the entire tread surface, making it easier to achieve good peak grip performance.

[0032] The rubber composition preferably contains more than 5 parts by mass of an ester-based plasticizer per 100 parts by mass of the rubber component.

[0033] It is believed that incorporating ester-based plasticizers into the rubber composition can further improve peak grip performance.

[0034] The rubber composition preferably contains more than 1 part by mass of an organic crosslinking agent per 100 parts by mass of the rubber component.

[0035] When an organic crosslinking agent is incorporated into a rubber composition, the distance between crosslinking points becomes longer compared to crosslinking with sulfur, allowing for greater energy loss and potentially resulting in better peak grip performance.

[0036] Preferably, the product of the glass transition temperature Tg2 (°C) of the rubber composition after acetone extraction and the amount of sulfur S in the rubber component is -50 or less.

[0037] It is believed that by satisfying the above equations for Tg2 and S, the mobility of the rubber component can be enhanced, making it easier to ensure good road surface conformity.

[0038] Preferably, the rubber composition further contains a resin component with a softening point of 90°C or lower.

[0039] It is believed that incorporating resin components with a softening point of 90°C or lower will further improve peak grip performance.

[0040] <Definition> A "standard rim" is the rim specified for each tire within the standardization system that includes the standard on which the tire is based. For example, it is called a "standard rim" for JATMA, a "design rim" for TRA, and a "measuring rim" for ETRTO.

[0041] "Regular internal pressure" refers to the air pressure specified for each tire by each standard within the tire standard system, including the standard on which the tire is based. For example, it is the "maximum air pressure" for JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and "INFLATION PRESSURE" for ETRTO.

[0042] "Normal condition" refers to a state in which the tire is mounted on a normal rim, filled to the normal internal pressure, and under no load. In this specification, unless otherwise specified, the dimensions of each part of the tire are measured under the aforementioned normal condition.

[0043] "Regular load" refers to the load specified for each tire by each standard within the standards system that the tire is based on. For example, it is the "maximum load capacity" for JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and "LOAD CAPACITY" for ETRTO.

[0044] "Land ratio R" refers to the ratio of the actual contact area to the total contact area at the tread contact surface. The methods for measuring the total contact area and the actual contact area will be described later.

[0045] "Acetone extraction" refers to the process of immersing a vulcanized rubber test piece in acetone for 72 hours to extract soluble components, in accordance with JIS K 6229. When preparing a test piece for acetone extraction by cutting it from a tire, it should be cut from the tire tread so that the tire circumference is the longer side and the tire radius is the thickness direction.

[0046] "Oil content" includes the amount of oil contained in the oil-applied rubber.

[0047] <Measurement method> The "tread contact shape" is obtained by mounting the tire onto a standard rim, applying the standard internal pressure, letting it stand at 25°C for 24 hours, then applying ink to the tire tread surface, applying the standard load, and pressing it onto paper at a camber angle of 0° to transfer the shape to the paper. The transfer is performed at 5 locations, rotating the tire 72° in the circumferential direction each time. Therefore, the contact shape is obtained 5 times.

[0048] The "total contact area" is the average of the areas obtained by the outer contour of the tread contact shape. The "actual contact area" is the average of the areas of the ink-marked areas of the tread contact shape. In other words, the land ratio is calculated using the following formula. Land ratio R = Average of the area of ​​5 points in the ink area / Average of the area obtained by the outer contour of the ground contact shape

[0049] The glass transition temperature (Tg) of a rubber composition is determined by measuring the temperature distribution curve of tanδ 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 3°C / min between -70°C and 40°C. The Tg is determined as the temperature corresponding to the largest tanδ value in the obtained temperature distribution curve (tanδ peak temperature). The sample for Tg measurement is prepared in the same manner as described later for 30°C tanδ. In this disclosure, the glass transition temperature (°C) of the rubber composition before acetone extraction is referred to as Tg1, and the glass transition temperature (°C) of the rubber composition before acetone extraction is referred to as Tg2.

[0050] "Sulfur content S in rubber components" is the amount of sulfur (mass%) measured by the oxygen combustion flask method in accordance with JIS K 6233:2016. Samples for sulfur content measurement are prepared by cutting them from tires.

[0051] "30℃tanδ" is the loss tangent measured under the conditions of 30℃ temperature, 10Hz frequency, 5% initial strain, and 1% dynamic strain. The sample used for loss tangent measurement is a vulcanized rubber composition measuring 20mm in length, 4mm in width, and 1mm in thickness. When preparing the sample by cutting it from a tire, it should be cut from the tire tread so that the tire circumference is the longer side and the tire radius is the thickness direction.

[0052] "0℃tanδ" is the loss loss tangent measured under conditions of 0℃ temperature, 10Hz frequency, 10% initial strain, and 2.5% dynamic strain. The sample for this measurement is prepared in the same manner as for 30℃tanδ.

[0053] "100℃tanδ" is the loss loss tangent measured under conditions of 100℃ temperature, 10Hz frequency, 10% initial strain, and 2.5% dynamic strain. The sample for this measurement is prepared in the same manner as for 30℃tanδ.

[0054] "E* 30 This is the complex modulus (MPa) measured under conditions of 30°C, 10Hz, 5% initial strain, and 1% dynamic strain. The sample for measuring the complex modulus is prepared in the same manner as for 30°C tanδ.

[0055] "Rubber hardness" is measured as Shore hardness (Hs) using a durometer type A under conditions of 23°C, in accordance with JIS K 6253-3:2012. The Shore hardness measurement sample is prepared by cutting it from the tread so that the tire radius is oriented in the thickness direction. The measurement is performed by pressing the measuring instrument against the sample from the contact surface side.

[0056] "Styrene content" is, 1 The value is calculated by 1H-NMR measurement and applies to 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 applies to 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 applies to rubber components having repeating units derived from butadiene, such as BR.

[0057] The "weight-average molecular weight (Mw)" can be determined by converting the measured value using gel permeation chromatography (GPC) (for example, the GPC-8000 series from Tosoh Corporation, with a differential refractometer as the detector and TSKGEL SUPERMALTIPORE HZ-M column from Tosoh Corporation) to a standard polystyrene equivalent. This method is applicable, for example, to SBR, BR, etc.

[0058] The "average primary particle size of carbon black" can be determined by observing with a transmission or scanning electron microscope, measuring 400 or more primary particles of carbon black observed within the field of view, and averaging the results. The "nitrogen adsorption specific surface area (N2SA) of carbon black" is measured in accordance with JIS K 6217-2:2017. The "oil absorption amount (DBP oil absorption amount (OAN)) of carbon black" is measured in accordance with JIS K6217-4:2017.

[0059] The "average primary particle size of silica" can be determined by observing with a transmission or scanning electron microscope, measuring 400 or more primary silica particles observed within the field of view, and averaging the results. The "nitrogen adsorption specific surface area (N2SA) of silica" is measured by the BET method in accordance with ASTM D3037-93.

[0060] The "softening point of the resin component" is the temperature at which the sphere descends when the softening point specified in JIS K 6220-1:2015 7.7 is measured using a ring-type softening point measuring device.

[0061] A tire manufacturing procedure, which is one embodiment of this disclosure, will be described in detail below. However, the following description is illustrative for the purpose of illustrating this disclosure and is not intended to limit the technical scope of this disclosure to this scope only.

[0062] <Tires> Figure 1 is a schematic diagram of the contact surface of the tread. A tread pattern is formed on the tread surface 1 that constitutes the tire according to this disclosure. A tire having the contact surface of Figure 1 is suitably used for passenger car tires.

[0063] In Figure 1, the tread has a plurality of circumferential grooves 4. The circumferential grooves 4 extend linearly along the circumferential direction C, but are not limited to this configuration, and may extend in a wavy, sinusoidal, or zigzag pattern along the circumferential direction, for example. In Figure 1, three circumferential grooves 4 are provided, but the number of circumferential grooves is not particularly limited in this disclosure and may be, for example, two to five. In this specification, "circumferential groove" refers to a groove that extends continuously in the tire circumferential direction C.

[0064] The shoulder land area 3 is a pair of land areas formed between the circumferential groove 4 and the tread edge Te. The center land area 2 is a land area formed between the pair of shoulder land areas 3. In Figure 1, two center land areas 2 are provided, but the number of center land areas is not particularly limited and may be, for example, one to five.

[0065] In Figure 1, the shoulder land portion 3 is provided with a widthwise groove 8 whose one end communicates with the circumferential groove 4, and widthwise grooves 5 and 6 whose ends do not communicate with the circumferential groove. The center land portion 2 is provided with a widthwise groove 7 whose one end communicates with the circumferential groove 4, and a groove 9 that extends in the tire width direction, crosses the center land portion 2, and whose ends communicate with the circumferential groove, but the configuration is not limited to this.

[0066] Figure 2 is a schematic diagram of the contact surface of a tire in another embodiment. A tire having the contact surface shown in Figure 2 is suitably used as a racing tire, and in particular suitably used as a racing tire for off-road driving.

[0067] In Figure 2, the tread portion 1 has a plurality of circumferential inclined grooves 10 extending diagonally with respect to the tire circumferential direction C, a circumferential groove 4 extending linearly along the circumferential direction C, a plurality of widthwise inclined grooves 11 extending diagonally with respect to the tire width direction W, and a widthwise groove 7 extending from the tread end in the tire width direction with one end communicating with the circumferential groove 4. The land portion formed by these grooves is divided into a plurality of blocks 12. The blocks 12 may have depressions (hereinafter referred to as recesses 13).

[0068] When the block 12 has a recess 13, the ratio of the volume of the recess 13 to the volume of the block 12 is preferably 0.08 or more, more preferably 0.10 or more, and even more preferably 0.12 or more. Furthermore, the ratio of the volume of the recess 13 to the volume of the block 12 is preferably 0.25 or less, more preferably 0.22 or less, and even more preferably 0.20 or less.

[0069] In the tires disclosed herein, the land ratio R at the contact surface of the tread is preferably 50% or more, more preferably 52% or more, even more preferably 55% or more, and particularly preferably 68% or more. If the land ratio R is less than 50%, the deformation of the tread portion will increase, and the effect of improving grip performance is thought to decrease. On the other hand, the land ratio R is preferably 85% or less, more preferably 80% or less, even more preferably 75% or less, and particularly preferably 72% or less. If the land ratio R is greater than 85%, the rubber of the tread portion cannot deform sufficiently, making it difficult to generate heat, and thus the effect of improving grip performance tends to decrease.

[0070] The glass transition temperature Tg2 of the rubber composition of this disclosure after acetone extraction is less than -45°C, preferably -46°C or lower, more preferably -50°C or lower, even more preferably -52°C or lower, even more preferably -54°C or lower, even more preferably -56°C or lower, even more preferably -60°C or lower, and particularly preferably -62°C or lower. On the other hand, from the viewpoint of the effects of this disclosure, the lower limit of the glass transition temperature Tg2 of the rubber composition of this disclosure after acetone extraction is preferably -85°C or higher, more preferably -80°C or higher, and even more preferably -75°C or higher.

[0071] In the tire of this disclosure, when the glass transition temperature after acetone extraction of the rubber composition is Tg2 (°C) and the land ratio at the contact surface of the tread is R (%), Tg2 and R satisfy the following formula (1). (10-1.25Tg2) / R>1.00···(1)

[0072] Here, as R increases, the value of equation (1) decreases, and conversely, as R decreases, the equivalent value increases. On the other hand, as Tg2 decreases, the value of equation (1) increases, and conversely, as Tg2 increases, the equivalent value decreases. Focusing on this point, we can adjust Tg2 and R to satisfy equation (1).

[0073] The value of formula (1) is greater than 1.00, preferably greater than 1.10, and more preferably greater than 1.20. Setting the value of formula (1) to greater than 1.00 provides good rigidity in combination with the high mobility and heat generation properties of the rubber, thereby improving peak grip performance. Furthermore, there is no particular upper limit to the value of formula (1), but from the viewpoint of the effects of this disclosure, it is preferably 3.00 or less, more preferably 2.50 or less, even more preferably 2.00 or less, even more preferably 1.80 or less, and particularly preferably 1.60 or less.

[0074] The glass transition temperature Tg1 of the rubber composition of this disclosure before acetone extraction is preferably -10°C or lower, more preferably -12°C or lower, even more preferably -13°C or lower, even more preferably -15°C or lower, even more preferably -18°C or lower, even more preferably -20°C or lower, even more preferably -21°C or lower, even more preferably -25°C or lower, and particularly preferably -30°C or lower. On the other hand, the lower limit of the glass transition temperature Tg1 of the rubber composition of this disclosure after acetone extraction is preferably -55°C or higher, more preferably -50°C or higher, even more preferably -45°C or higher, and particularly preferably -42°C or higher, from the viewpoint of the effects of this disclosure.

[0075] From the viewpoint of the effects of this disclosure, the difference in glass transition temperature (Tg1-Tg2) before and after acetone extraction of the rubber composition is preferably 25°C or higher, more preferably 30°C or higher, and even more preferably 32°C or higher. Furthermore, from the viewpoint of the effects of this disclosure, Tg1-Tg2 is preferably 55°C or lower, more preferably 48°C or lower, and even more preferably 40°C or lower.

[0076] From the viewpoint of preventing excessive restriction of polymer molecular chains in the rubber composition of the rubber composition of this disclosure and a decrease in mobility, the sulfur content S in the rubber component is preferably 1.3% by mass or less, more preferably 1.2% by mass or less, even more preferably 0.95% by mass or less, even more preferably 0.92% by mass or less, and even more preferably 0.90% by mass or less. On the other hand, from the viewpoint of the effects of this disclosure, the sulfur content S in the rubber component of the rubber composition of this disclosure is preferably 0.50% by mass or more, more preferably 0.55% by mass or more, even more preferably 0.60% by mass or more, and particularly preferably 0.65% by mass or more.

[0077] From the viewpoint of the effects of this disclosure, the product of the glass transition temperature (Tg2) after acetone extraction of the rubber composition of this disclosure and the amount of sulfur S in the rubber component (Tg2×S) is preferably -40 or less, more preferably -45 or less, even more preferably -48 or less, and particularly preferably -50 or less. Furthermore, from the viewpoint of the effects of this disclosure, Tg2×S is preferably -70 or more, more preferably -67 or more, and even more preferably -65 or more.

[0078] From the viewpoint of obtaining good rigidity and improving peak grip performance, the rubber hardness of the rubber composition disclosed herein is preferably greater than 62, more preferably greater than 63, even more preferably greater than 64, and particularly preferably greater than 65. Furthermore, from the viewpoint of grip performance, it is preferably less than 75, more preferably less than 74, even more preferably less than 73, and particularly preferably less than 72.

[0079] From the viewpoint of grip performance, the tanδ at 0°C of the rubber composition disclosed herein is preferably greater than 0.40, more preferably greater than 0.42, and even more preferably greater than 0.44. On the other hand, from the viewpoint of blow resistance performance, the tanδ at 0°C of the rubber composition is preferably less than 1.00, more preferably less than 0.85, and even more preferably less than 0.75.

[0080] From the viewpoint of grip performance, the 30°C tanδ of the rubber composition disclosed herein is preferably greater than 0.20.

[0081] When the rubber composition of this disclosure is used as a racing tire, the 30°C tanδ is more preferably greater than 0.35, even more preferably greater than 0.40, and particularly preferably greater than 0.45. Furthermore, when used as a racing tire, the 30°C tanδ is preferably less than 0.55, more preferably less than 0.52, and even more preferably less than 0.50.

[0082] When the rubber composition of this disclosure is used as a tire for a passenger car, the 30°C tanδ is more preferably greater than 0.24, even more preferably greater than 0.25, and particularly preferably greater than 0.30. Furthermore, when used as a tire for a passenger car, the 30°C tanδ is preferably less than 0.40, more preferably less than 0.38, and even more preferably less than 0.35.

[0083] From the viewpoint of grip performance, the 100°C tanδ of the rubber composition disclosed herein is preferably greater than 0.08.

[0084] When the rubber composition of this disclosure is used as a racing tire, the 100°C tanδ is preferably greater than 0.30, and more preferably greater than 0.33. Furthermore, when used as a racing tire, the 100°C tanδ is preferably less than 0.45, and more preferably less than 0.40, from the viewpoint of blow-off resistance.

[0085] When the rubber composition of this disclosure is used as a passenger car tire, the 100°C tanδ is preferably greater than 0.08, and more preferably greater than 0.09. Furthermore, when used as a passenger car tire, the 100°C tanδ is preferably less than 0.20, and more preferably less than 0.18, from the viewpoint of blow-off resistance.

[0086] The tire of this disclosure preferably has a product of 100°C tanδ and land ratio R(%) of 5.0 or more. Furthermore, there is no particular upper limit to the product of 100°C tanδ and land ratio R(%), but from the viewpoint of the effects of this disclosure, it is preferably 35 or less, more preferably 32 or less, and even more preferably 30 or less.

[0087] When the rubber composition of this disclosure is used as a racing tire, the product of tanδ at 100°C and the land ratio R (%) is preferably 15 or more, more preferably 20 or more, and even more preferably 21 or more.

[0088] When the rubber composition of the present disclosure is used as a passenger car tire, the product of the tan δ at 100 °C and the land ratio R (%) is more preferably 6.0 or more, and even more preferably 7.0 or more. When used as a passenger car tire, the product of the tan δ at 100 °C and the land ratio R (%) is preferably 15 or less, more preferably 12 or less, and even more preferably 10 or less.

[0089] The complex elastic modulus E* of the rubber composition of the present disclosure at 30 °C 30 is preferably less than 30 MPa from the viewpoint of grip performance.

[0090] When the rubber composition of the present disclosure is used as a competition tire, E* 30 is more preferably less than 25 MPa, and even more preferably less than 20 MPa. Also, E* when used as a competition tire 30 is preferably more than 7 MPa, more preferably more than 10 MPa, and even more preferably more than 15 MPa.

[0091] When the rubber composition of the present disclosure is used as a passenger car tire, E* 30 is more preferably less than 12 MPa, and even more preferably less than 10 MPa. E* when used as a passenger car tire 30 is preferably more than 2 MPa, more preferably more than 3 MPa, and even more preferably more than 4 MPa.

[0092] In addition, Tg1, Tg2, rubber hardness, tan δ at 0 °C, tan δ at 30 °C, and E* at 30 °C of the rubber composition of the present disclosure 30The following can be adjusted as appropriate by changing the type and amount of rubber components, fillers, softeners, etc. For example, Tg1 can be lowered by lowering the glass transition temperature of the rubber components, lowering the styrene content in the rubber components, lowering the glass transition temperature of the softener, etc. Tg2 can be lowered by lowering the glass transition temperature of the rubber components, lowering the styrene content in the rubber components, etc. Rubber hardness can be increased by increasing the amount of fillers in the rubber composition and decreasing the amount of softeners such as oil. 0℃tanδ, 30℃tanδ, and 100℃tanδ can be increased by increasing the amount of fillers in the rubber composition and reducing the particle size of the fillers, etc. E* 30 This can be increased by increasing the amount of filler in the rubber composition, decreasing the amount of softening agent, and so on.

[0093] [Rubber composition] The tread portion of this disclosure is characterized in that the land ratio R at the contact surface of the tread portion and the glass transition temperature Tg2 of the rubber composition after acetone extraction satisfy (10 - 1.25Tg2) / R > 1.00. The rubber composition constituting the tread portion can be manufactured using the raw materials described below, according to the physical properties of the required rubber composition. This will be explained in detail below.

[0094] <Rubber components> The rubber composition of this disclosure contains a rubber component. Preferably, the rubber component contains styrene-butadiene rubber (SBR), and may consist solely of SBR. The rubber component may also contain isoprene rubber and / or butadiene rubber (BR). When used in passenger car tires, it is preferable to use SBR and BR in combination, and more preferably to use SBR, BR, and isoprene rubber in combination.

[0095] (SBR) There are no particular limitations on the type of SBR, and examples include unmodified solution-polymerized SBR (S-SBR), emulsion-polymerized SBR (E-SBR), and modified SBRs of these (modified S-SBR, modified E-SBR). Modified SBRs include SBRs with modified terminals and / or main chains, and modified SBRs coupled with tin, silicon compounds, etc. (condensates, branched structures, etc.). Among these, S-SBR and modified SBRs are preferred. Furthermore, hydrogenated SBRs (hydrogenated SBRs) can also be used. Oil-expanded SBRs or non-oil-expanded SBRs can be used.

[0096] SBR is considered effective in improving peak grip performance because it exhibits excellent viscoelastic properties in the region highly correlated with peak grip performance, as well as superior compatibility and responsiveness with fillers.

[0097] The SBRs listed above may be used individually or in combination of two or more. Examples of the SBRs listed above include those commercially available from Asahi Kasei Corporation, JSR Corporation, Sumitomo Chemical Co., Ltd., Nippon Zeon Co., Ltd., ZS Elastomer Co., Ltd., etc.

[0098] From the viewpoint of peak grip performance and wear resistance, the styrene content of SBR is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. Furthermore, from the viewpoint of temperature dependence of grip performance and blow resistance, it is preferably 35% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less. The styrene content of SBR is measured by the measurement method described above.

[0099] The vinyl content of SBR is preferably 10 mol% or more, more preferably 12 mol% or more, and even more preferably 15 mol% or more, from the viewpoint of ensuring reactivity with fillers, peak grip performance, and abrasion resistance. Furthermore, the vinyl content of SBR is preferably 70 mol% or less, more preferably 60 mol% or less, even more preferably 50 mol% or less, and particularly preferably 40 mol% or less, from the viewpoint of preventing increased temperature dependence, elongation at break, and abrasion resistance. The vinyl content of SBR is measured by the measurement method described above.

[0100] From the viewpoint of peak grip performance, the weight-average molecular weight (Mw) of SBR is preferably 150,000 or more, more preferably 200,000 or more, and even more preferably 250,000 or more. Furthermore, 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. The weight-average molecular weight of SBR is measured by the measurement method described above.

[0101] When SBR is included, its content in the rubber component is preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 50% by mass or more, and particularly preferably 60% by mass or more, from the viewpoint of the effects of this disclosure. Furthermore, the upper limit of the SBR content is not particularly limited and can be, for example, 100% by mass, 95% by mass or less, 90% by mass or less, 85% by mass or less, or 80% by mass or less.

[0102] (BR) The BR is not particularly limited, and for example, 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 synthesized using a rare-earth element catalyst (rare-earth BR), BR containing syndiotactic polybutadiene crystals (SPB-containing BR), modified BR (high-cis modified BR, low-cis modified BR), etc., which are common in the tire industry, can be used. These BRs may be used individually or in combination of two or more. The cis content of the BR is measured by the measurement method described above.

[0103] High-cis BR can be commercially available from companies such as Nippon Zeon Co., Ltd., Ube Industries, Ltd., and JSR Corporation. Including high-cis BR can improve low-temperature properties and wear resistance. The cis content of high-cis BR 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. The cis content of BR is measured by the measurement method described above.

[0104] From the viewpoint of wear resistance, the weight-average molecular weight (Mw) of 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 1,500,000 or less, and even more preferably 1,000,000 or less. The Mw of BR is measured by the measurement method described above.

[0105] When BR is included, its content in the rubber component is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less, from the viewpoint of the effects of this disclosure. Furthermore, there is no particular lower limit to the content, but from the viewpoint of peak grip performance, 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.

[0106] (Isoprene rubber) Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. For NR, for example, commonly used rubbers in the tire industry such as SIR20, RSS#3, and TSR20 can be used. These isoprene-based rubbers may be used individually or in combination of two or more types.

[0107] When isoprene-based rubber is included, its content in 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 peak grip performance. Furthermore, there is no particular lower limit to the content, but from the viewpoint of initial grip performance, 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.

[0108] (Other rubber components) The rubber component may contain other rubber components other than SBR, BR, and isoprene-based rubber, to the extent that it does not affect the effects of this disclosure. Other rubber components may include crosslinkable rubber components commonly used in the tire industry, such as diene-based rubbers like styrene-isoprene rubber (SIR), styrene-isoprene butadiene rubber (SIBR), chloroprene rubber (CR), and acrylonitrile butadiene rubber (NBR); and non-diene-based rubbers other than butyl-based rubbers such as hydrogenated nitrile rubber (HNBR), ethylene propylene rubber, polynorbornene rubber, silicone rubber, polyethylene chloride rubber, fluororubber (FKM), acrylic rubber (ACM), and hydrin rubber. These other rubber components may be used individually or in combination of two or more. The content of diene-based rubber in the rubber component is preferably 80% by mass or more. In addition to the above rubber components, known thermoplastic elastomers may or may not be included.

[0109] <Filler> The rubber composition of this disclosure contains a filler. The filler preferably contains carbon black and / or silica, and more preferably carbon black. The filler may also consist only of carbon black and silica, or only of carbon black.

[0110] (silica) The silica used is not particularly limited; for example, silica prepared by the dry process (anhydrous silica) or silica prepared by the wet process (hydrated silica), which are common in the tire industry, can be used. In addition, silica obtained from biomass materials such as rice husks may also be used. These silicas may be used individually or in combination of two or more types.

[0111] From the viewpoint of peak grip performance, the average primary particle diameter of silica is preferably 20 nm or less, more preferably 16 nm or less, and even more preferably 15 nm or less. From the viewpoint of dispersibility, it is preferably 5 nm or more, more preferably 8 nm or more, and even more preferably 10 nm or more. The average primary particle diameter of silica is measured by the measurement method described above.

[0112] The nitrogen adsorption specific surface area (N2SA) of silica is considered to be 100m² from the viewpoint of ensuring reinforcing properties and peak grip performance. 2 Preferably 120m / g or more. 2 More preferably 140m / g or more. 2 More preferably 150m / g or more. 2 A concentration of 350m or more is particularly preferred. Furthermore, from the viewpoint of dispersibility, 350m is preferable. 2 Preferably less than / g, 300m 2 More preferably less than / g, 250m 2 A value of less than / g is even more preferable. The N2SA of silica is measured by the measurement method described above.

[0113] When silica is included, its content per 100 parts by mass of the rubber component is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, even more preferably 30 parts by mass or less, and particularly preferably less than 10 parts by mass, from the viewpoint of reinforcing the rubber composition when the rubber composition of this disclosure is used in racing tires. When the rubber composition of this disclosure is used in racing tires, it is not necessary to include silica.

[0114] When silica is included, the silica content per 100 parts by mass of the rubber component is preferably 80 parts by mass or more, more preferably 100 parts by mass or more, and even more preferably 120 parts by mass or more, when the rubber composition of this disclosure is used in passenger car tires, from the viewpoint of peak grip performance. Furthermore, there is no particular upper limit, but it is preferably 300 parts by mass or less, more preferably 250 parts by mass or less, and even more preferably 200 parts by mass or less.

[0115] (Carbon Black) The carbon black used is not particularly limited; for example, common types used in the tire industry such as GPF, FEF, HAF, ISAF, and SAF can be used. These carbon blacks may be used individually or in combination of two or more types. Furthermore, from a life cycle assessment perspective, in addition to the above-mentioned carbon blacks, carbon black made from lignin or recycled carbon black obtained by thermal decomposition from products containing carbon black, such as tires, may also be used.

[0116] From the viewpoint of reinforcing properties and peak grip performance, the average primary particle size of carbon black is preferably 35 nm or less, more preferably 30 nm or less, even more preferably 28 nm or less, even more preferably 20 nm or less, and particularly preferably 19 nm or less. From the viewpoint of dispersibility, it is preferably 10 nm or more, more preferably 12 nm or more, and even more preferably 15 nm or more. The average primary particle size of carbon black is measured by the measurement method described above.

[0117] The nitrogen adsorption specific surface area (N2SA) of carbon black is 50m², from the perspective of reinforcement and peak grip performance. 2 Preferably 70m / g or more. 2 More preferably 100m / g or more, 2 More preferably 120m / g or more. 2 A concentration of 250m or more is particularly preferred. Furthermore, from the viewpoint of dispersibility, 250m is preferable. 2 Preferably less than / g, 220m 2A value of less than / g is more preferable. The N2SA of carbon black is measured by the measurement method described above.

[0118] From the viewpoint of reinforcing properties and peak grip performance, the oil absorption capacity (DBP oil absorption capacity (OAN)) of carbon black is preferably 85 mL / 100g or more, more preferably 90 mL / 100g or more, and even more preferably 100 mL / 100g or more. Furthermore, from the viewpoint of grip performance, the OAN is preferably 250 mL / 100g or less, more preferably 225 mL / 100g or less, and even more preferably 200 mL / 100g or less. The OAN of carbon black is measured by the measurement method described above.

[0119] When carbon black is included, the content per 100 parts by mass of the rubber component is preferably 40 parts by mass or more, more preferably more than 50 parts by mass, and even more preferably 100 parts by mass or more, from the viewpoint of weather resistance and reinforcing properties when the rubber composition of this disclosure is used in racing tires. Furthermore, there is no particular upper limit, but it is preferably 190 parts by mass or less, more preferably 150 parts by mass or less, and even more preferably 140 parts by mass or less.

[0120] When carbon black is included, the content per 100 parts by mass of the rubber component is preferably more than 1 part by mass, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, from the viewpoint of weather resistance and reinforcing properties when the rubber composition of this disclosure is used in passenger car tires. From the viewpoint of low fuel consumption performance, it is preferably less than 150 parts by mass, more preferably less than 135 parts by mass, and even more preferably less than 120 parts by mass.

[0121] (Other fillers) Other fillers commonly used in the tire industry, such as aluminum hydroxide, calcium carbonate, alumina, clay, and talc, can be added. Biochar may also be used.

[0122] In this disclosure, the total filler content per 100 parts by mass of rubber component is, from the viewpoint of peak grip performance, more than 100 parts by mass, preferably more than 105 parts by mass, more preferably more than 110 parts by mass, even more preferably 120 parts by mass or more, and particularly preferably 130 parts by mass or more. Furthermore, the upper limit of the total filler content per 100 parts by mass of rubber component is, from the viewpoint of the effects of this disclosure, preferably 200 parts by mass or less, more preferably 180 parts by mass or less, even more preferably 150 parts by mass or less, and particularly preferably 140 parts by mass or less.

[0123] (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 conventionally been 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, and 2-mercaptoethyltriethoxysilane; sulfide-based silane coupling agents such as bis(3-triethoxysilylpropyl) disulfide and bis(3-triethoxysilylpropyl) tetrasulfide; 3-octanoylthio-1-propyltriethoxysilane, 3-hexanoylthio-1-propyltriethoxysilane, and 3-octanoylthio-1-propyltrimethoxysilane. Examples include thioester silane coupling agents such as lan; vinyl silane coupling agents such as vinyltriethoxysilane and vinyltrimethoxysilane; amino silane coupling agents such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and 3-(2-aminoethyl)aminopropyltriethoxysilane; glycidoxy silane coupling agents such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro silane coupling agents such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Among these, it is preferable to contain a sulfide silane coupling agent. As silane coupling agents, for example, those commercially available from Evonik Degussa, etc., can be used. These silane coupling agents may be used individually or in combination of two or more.

[0124] When a silane coupling agent is included, the amount of silica per 100 parts by mass of the rubber component is preferably more than 1.0 part by mass, more preferably more than 2.0 parts by mass, more preferably more than 3.0 parts by mass, even more preferably more than 5.0 parts by mass, and particularly preferably 8.0 parts by mass or more, from the viewpoint of improving the dispersibility of silica. Furthermore, from the viewpoint of preventing a decrease in wear resistance, it is preferably less than 20 parts by mass, more preferably less than 15 parts by mass, and even more preferably less than 12 parts by mass.

[0125] From the viewpoint of improving silica dispersibility, the content of the silane coupling agent per 100 parts by mass of silica is preferably more than 2.0 parts by mass, more preferably more than 4.0 parts by mass, and even more preferably 6.0 parts by mass or more. Furthermore, from the viewpoint of cost and processability, it is preferably less than 25 parts by mass, more preferably less than 20 parts by mass, and even more preferably less than 18 parts by mass.

[0126] <Softener> The rubber composition according to this disclosure preferably contains a softening agent. Examples of softening agents include resin components, oils, liquid rubber, and ester-based plasticizers. Softening agents also include stretching oils, stretching resins, and stretching liquid rubber components of rubber components that have been stretched using oil stretching, resin stretching, or liquid rubber stretching. These softening agents may be derived from petroleum or biomass. In addition, low molecular weight hydrocarbon components obtained by thermal decomposition and extraction of used tires or products containing various components may be used as softening agents.

[0127] (Resin components) The resin components are not particularly limited, but examples include petroleum resins, terpene resins, rosin resins, and phenolic resins commonly used in the tire industry. These resin components may be used individually or in combination of two or more.

[0128] Examples of petroleum resins include C5-based petroleum resins, aromatic petroleum resins, and C5C9-based petroleum resins, and from the viewpoint of the effects of this disclosure, aromatic petroleum resins are preferred.

[0129] In this specification, "C5 petroleum resin" refers to a resin obtained by polymerizing a C5 fraction. Examples of C5 fractions include petroleum fractions with 4 to 5 carbon atoms, such as cyclopentadiene, pentene, pentadiene, and isoprene. Dicyclopentadiene resin (DCPD resin) is preferably used as the C5 petroleum resin.

[0130] In this specification, "aromatic petroleum resin" refers to a resin obtained by polymerizing a C9 fraction, which may be hydrogenated or modified. Examples of C9 fractions include petroleum fractions with 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, indene, and methylindene. Specific examples of aromatic petroleum resins include, for example, Coumaron indene resin, coumaron resin, indene resin, and aromatic vinyl resins are suitably used. As aromatic vinyl resins, homopolymers of α-methylstyrene or styrene, or copolymers of α-methylstyrene and styrene are preferred, and copolymers of α-methylstyrene and styrene are more preferred, for reasons of being economical, easy to process, and having excellent heat generation properties. As aromatic vinyl resins, commercially available products from companies such as Kraton and Eastman Chemical can be used.

[0131] In this specification, "C5C9 petroleum resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, and may be hydrogenated or modified. Examples of the C5 fraction and C9 fraction include the petroleum fractions mentioned above. As C5C9 petroleum resin, commercially available products from companies such as Tosoh Corporation and LUHUA can be used.

[0132] Examples of terpene resins include polyterpene resins, terpene phenol resins, and terpene styrene resins. These may be used individually or in combination of two or more. Among these, terpene styrene resins are preferred because they have particularly good compatibility with SBR and allow sulfur to disperse easily within the rubber component.

[0133] In this specification, "polyterpene resin" refers to a resin made from at least one terpene compound selected from α-pinene, β-pinene, limonene, dipentene, etc. Terpene phenol resin is a resin made from the above-mentioned terpene compound and phenolic compound. Terpene styrene resin is a resin made from the above-mentioned terpene compound and styrene.

[0134] The terpene resin may be a hydrogenated resin (e.g., hydrogenated polyterpene resin, hydrogenated terpene styrene resin). Hydrogenation of the terpene resin can be carried out by known methods, or commercially available hydrogenated resins can be used.

[0135] In this disclosure, commercially available terpene resins may be used. Examples of such commercially available products include those manufactured and sold by Yasuhara Chemical Co., Ltd., etc.

[0136] Rosin-based resins are not particularly limited, but examples include natural resin rosin and rosin-modified resins obtained by hydrogenation, disproportionation, dimerization, esterification, etc.

[0137] Phenolic resins are not particularly limited, but examples include phenol-formaldehyde resin, alkylphenol-formaldehyde resin, alkylphenol-acetylene resin, and oil-modified phenol-formaldehyde resin.

[0138] From the viewpoint of peak grip performance, the softening point of the resin component is preferably 200°C or lower, and more preferably 150°C or lower. From the viewpoint of processability, it is preferably 70°C or higher, and more preferably 80°C or higher. The softening point of the resin component is measured by the measurement method described above. Furthermore, the softening point of the resin is generally about 45°C ± 5°C higher than the glass transition point of the resin measured by DSC.

[0139] When a resin component is included, the content of the rubber component per 100 parts by mass is preferably more than 15 parts by mass, more preferably more than 20 parts by mass, even more preferably more than 25 parts by mass, even more preferably more than 30 parts by mass, and particularly preferably 35 parts by mass or more, from the viewpoint of peak grip performance. Furthermore, from the viewpoint of processability, it is preferably less than 90 parts by mass, more preferably less than 70 parts by mass, even more preferably less than 60 parts by mass, and particularly preferably less than 50 parts by mass.

[0140] (oil) Examples of oils include process oils, vegetable oils, and animal fats. Examples of process oils include paraffinic process oils, naphthenic process oils, and aromatic process oils. Furthermore, for environmental reasons, process oils with a low content of polycyclic aromatic compounds (PCA) can be used. Examples of low-PCA process oils include light extraction solvates (MES), processed distillate aromatic extracts (TDAEs), and heavy naphthenic oils. In addition to the above oils, from the perspective of life cycle assessment, used lubricating oils that have been used in rubber mixers and engines, or used cooking oils from restaurants that have been appropriately refined may also be used.

[0141] When oil is included, the content of the oil per 100 parts by mass of rubber component is preferably more than 5 parts by mass, more preferably more than 10 parts by mass, even more preferably more than 15 parts by mass, and particularly preferably 20 parts by mass or more, from the viewpoint of processability. Furthermore, from the viewpoint of wear resistance and rubber hardness, it is preferably less than 100 parts by mass, more preferably less than 80 parts by mass, and even more preferably less than 60 parts by mass.

[0142] (Liquid rubber) The rubber composition of this disclosure preferably contains liquid rubber. 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), but examples 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 individually or in combination of two or more.

[0143] When liquid rubber is included, its content per 100 parts by mass of rubber component is preferably more than 1 part by mass, more preferably more than 5 parts by mass, even more preferably more than 10 parts by mass, even more preferably more than 15 parts by mass, and particularly preferably 20 parts by mass or more. Furthermore, the liquid rubber content is preferably less than 60 parts by mass, more preferably less than 50 parts by mass, and even more preferably less than 40 parts by mass.

[0144] (Ester-based plasticizers) Examples of ester-based plasticizers include dibutyl adipate (DBA), diisobutyl adipate (DIBA), dioctyl adipate (DOA), di-2-ethylhexyl azelaate (DOZ), dibutyl sebacate (DBS), diisononyl adipate (DINA), diethyl phthalate (DEP), dioctyl phthalate (DOP), diundecyl phthalate (DUP), dibutyl phthalate (DBP), dioctyl sebacate (DOS), tributyl phosphate (TBP), trioctyl phosphate (TOP), triethyl phosphate (TEP), trimethyl phosphate (TMP), thymidine triphosphate (TTP), tricresyl phosphate (TCP), and trixylenyl phosphate (TXP), among which dioctyl sebacate (DOS) is preferred. These ester-based plasticizers may be used individually or in combination of two or more.

[0145] When an ester-based plasticizer is included, the content per 100 parts by mass of the rubber component is preferably more than 1 part by mass, more preferably more than 3 parts by mass, and even more preferably 5 parts by mass or more, from the viewpoint of the effects of this disclosure. Furthermore, from the viewpoint of peak grip performance, it is preferably less than 50 parts by mass, more preferably less than 40 parts by mass, and even more preferably less than 30 parts by mass.

[0146] The total content of the resin component and ester-based plasticizer per 100 parts by mass of the rubber component is preferably more than 5 parts by mass, more preferably more than 10 parts by mass, even more preferably more than 14 parts by mass, even more preferably more than 19 parts by mass, and particularly preferably more than 24 parts by mass. Furthermore, the content is preferably less than 80 parts by mass, more preferably less than 70 parts by mass, even more preferably less than 60 parts by mass, and particularly preferably less than 66 parts by mass. By setting the total content of the resin component and ester-based plasticizer within the above range, the peak grip performance can be improved.

[0147] From the viewpoint of peak grip performance, the content of the softener per 100 parts by mass of the rubber component (total amount if multiple softeners are used in combination) is preferably more than 40 parts by mass, more preferably more than 50 parts by mass, even more preferably more than 60 parts by mass, and particularly preferably 65 parts by mass or more. From the viewpoint of processability, it is preferably less than 140 parts by mass, more preferably less than 120 parts by mass, even more preferably less than 101 parts by mass, and particularly preferably less than 91 parts by mass.

[0148] <Other compounding agents> In addition to the components mentioned above, the rubber composition relating to this disclosure may appropriately contain compounding agents commonly used in the tire industry, such as waxes, processing aids, antioxidants, stearic acid, zinc oxide, crosslinking agents, vulcanization accelerators, and the like.

[0149] When wax is included, the amount of wax per 100 parts by mass of rubber component is preferably more than 0.5 parts by mass, more preferably more than 1.0 part by mass, and even more preferably more than 1.5 parts by mass, from the viewpoint of weather resistance of the rubber. Furthermore, from the viewpoint of preventing whitening of the tire due to bloom, it is preferably less than 10 parts by mass, more preferably less than 7.0 parts by mass, and even more preferably less than 5.0 parts by mass.

[0150] While not particularly limited, examples of anti-aging agents include amine-based, quinoline-based, quinone-based, phenol-based, and imidazole-based compounds, as well as metal carbamate salts. Phenylenediamine-based anti-aging agents 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 anti-aging agents such as 2,2,4-trimethyl-1,2-dihydroquinoline polymer and 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline are preferred. These anti-aging agents may be used individually or in combination of two or more.

[0151] When an anti-aging agent is included, the content per 100 parts by mass of rubber component is preferably more than 0.5 parts by mass, more preferably more than 1.0 part by mass, and even more preferably more than 1.5 parts by mass, from the viewpoint of the rubber's resistance to ozone cracking. Furthermore, from the viewpoint of wear resistance and wet grip performance, it is preferably less than 10 parts by mass, more preferably less than 8.0 parts by mass, and even more preferably less than 5.0 parts by mass.

[0152] When stearic acid is included, its content per 100 parts by mass of rubber component is preferably more than 0.5 parts by mass, more preferably more than 1.0 part by mass, and even more preferably more than 1.5 parts by mass, from the viewpoint of processability. Furthermore, from the viewpoint of vulcanization rate, it is preferably less than 10 parts by mass, more preferably less than 8.0 parts by mass, and even more preferably less than 5.0 parts by mass.

[0153] When zinc oxide is included, its content per 100 parts by mass of rubber component is preferably more than 0.5 parts by mass, more preferably more than 1.0 part by mass, and even more preferably more than 1.5 parts by mass, from the viewpoint of processability. Furthermore, from the viewpoint of wear resistance, it is preferably less than 10 parts by mass, more preferably less than 8.0 parts by mass, and even more preferably less than 5.0 parts by mass.

[0154] Sulfur is preferably used as a crosslinking agent. Suitable sulfur varieties include powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersible sulfur.

[0155] When sulfur is included, the content per 100 parts by mass of rubber component is preferably more than 0.1 parts by mass, more preferably more than 0.3 parts by mass, even more preferably 0.5 parts by mass or more, and particularly preferably more than 0.5 parts by mass, from the viewpoint of ensuring a sufficient vulcanization reaction. Furthermore, from the viewpoint of preventing deterioration, it is preferably less than 5.0 parts by mass, more preferably less than 4.0 parts by mass, even more preferably less than 3.0 parts by mass, and particularly preferably less than 2.6 parts by mass. When oil-containing sulfur is used as a crosslinking agent, the content of the vulcanizing agent shall be the total content of pure sulfur contained in the oil-containing sulfur.

[0156] As a crosslinking agent other than sulfur, known organic crosslinking agents can also be used. When an organic crosslinking agent is incorporated, the distance between crosslinking points becomes longer compared to crosslinking with sulfur, allowing for greater energy loss and resulting in good peak grip performance.

[0157] The organic crosslinking agent is not particularly limited as long as it can form crosslinking chains other than polysulfide bonds, but examples include alkylphenol-sulfur chloride condensates, 1,6-hexamethylene-dithiosulfate sodium dihydrate, 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane, and dicumyl peroxide, with 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane being preferred. These organic crosslinking agents can be commercially available from companies such as Taoka Chemical Industries, Ltd., Lanxess Corporation, and Flexis.

[0158] When an organic crosslinking agent is included, its content per 100 parts by mass of the rubber component is preferably more than 1 part by mass, more preferably more than 2 parts by mass, and even more preferably more than 3 parts by mass. Furthermore, the content is preferably less than 10 parts by mass, more preferably less than 8 parts by mass, and even more preferably less than 6 parts by mass.

[0159] Examples of vulcanization accelerators include sulfenamide-based vulcanization accelerators, thiazole-based vulcanization accelerators, thiram-based vulcanization accelerators, guanidine-based vulcanization accelerators, dithiocarbamate-based vulcanization accelerators, and caprolactam disulfide. These vulcanization accelerators may be used individually or in combination of two or more. Among these, sulfenamide-based vulcanization accelerators, thiazole-based vulcanization accelerators, and guanidine-based vulcanization accelerators are preferred because they more favorably produce the desired effect. A vulcanization accelerator consisting of one or more agents selected from the group comprising [the specified components] is preferred.

[0160] Examples of sulfenamide-based vulcanization accelerators include Nt-butyl-2-benzothiazole sulfenamide (TBBS), N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS), and N,N-dicyclohexyl-2-benzothiazolyl sulfenamide (DCBS). Among these, TBBS and CBS are preferred.

[0161] Examples of thiazole-based vulcanization accelerators include 2-mercaptobenzothiazole (MBT) or its salts, di-2-benzothiazolyl disulfide (MBTS), 2-(2,4-dinitrophenyl)mercaptobenzothiazole, and 2-(2,6-diethyl-4-morpholinothio)benzothiazole. Of these, MBTS and MBT are preferred, with MBTS being more preferred.

[0162] Examples of thiram-based vulcanization accelerators include tetrakis(2-ethylhexyl)thiram disulfide (TOT-N), tetramethylthiram disulfide (TMTD), tetraethylthiram disulfide, tetramethylthiram monosulfide (TMTM), dipentamethylenethiram disulfide, and dipentamethylenethiram tetrasulfide. Among these, TOT-N and TMTD are preferred, with TOT-N being more preferred.

[0163] Examples of guanidine-based vulcanization accelerators include 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salts of dicatecholborate, 1,3-di-o-cumenylguanidine, 1,3-di-o-biphenylguanidine, and 1,3-di-o-cumenyl-2-propionylguanidine. Among these, DPG is preferred.

[0164] Examples of dithiocarbamate-based vulcanization accelerators include piperidinium pentamethylenedithiocarbamate (PPDC), zinc dimethyldithiocarbamate (ZnMDC), zinc diethyldithiocarbamate (ZnEDC), zinc dibutyldithiocarbamate (ZnBDC), zinc dibenzyldithiocarbamate (ZDBzC), zinc N-ethyl-N-phenyldithiocarbamate (ZnEPDC), zinc N-pentamethylenedithiocarbamate (ZnPDC), sodium dibutyldithiocarbamate (NaBDC), copper dimethyldithiocarbamate (CuMDC), iron dimethyldithiocarbamate (FeMDC), and tellurium diethyldithiocarbamate (TeEDC). Among these, ZnBDC and ZDBzC are preferred.

[0165] Examples of caprolactam disulfides include N,N'-di(δ-caprolactam) disulfide, N,N'-di(ε-caprolactam) disulfide, N,N'-di(3-methyl-δ-caprolactam) disulfide, N,N'-di(3-ethyl-ε-caprolactam) disulfide, N,N'-di(δ-methoxy-ε-caprolactam) disulfide, N,N'-di(3-chlor-ε-caprolactam) disulfide, N,N'-di(δ-nitro-ε-caprolactam) disulfide, and N,N'-di(3-amino-ε-caprolactam) disulfide. Among these, N,N'-di(ε-caprolactam) disulfide is preferred.

[0166] When a vulcanization accelerator is included, its content per 100 parts by mass of the rubber component (total amount if multiple vulcanization accelerators are used in combination) is preferably more than 2.0 parts by mass, and more preferably more than 2.5 parts by mass. Furthermore, the content of the vulcanization accelerator per 100 parts by mass of the rubber component is preferably less than 10 parts by mass, and more preferably less than 7 parts by mass. By keeping the content of the vulcanization accelerator within the above range, it tends to be possible to ensure fracture strength and elongation.

[0167] <Manufacturing> The rubber composition relating to this disclosure can be manufactured by known methods. For example, it can be manufactured by kneading each of the above components using a rubber kneading device such as an open roll or a closed kneader (Banbury mixer, kneader, etc.).

[0168] The mixing process includes, for example, a base mixing process in which compounding agents and additives other than the vulcanizing agent and vulcanization accelerator are mixed, and a final mixing (F mixing) process in which the vulcanizing agent and vulcanization accelerator are added to the mixture obtained in the base mixing process and mixed. Furthermore, the base mixing process can be divided into multiple processes as desired.

[0169] There are no particular limitations on the mixing conditions, but for example, in the base mixing process, mixing is performed at a discharge temperature of 150-170°C for 3-10 minutes, and in the final mixing process, mixing is performed at 70-110°C for 1-5 minutes. There are no particular limitations on the vulcanization conditions, but for example, vulcanization is performed at 150-200°C for 10-30 minutes.

[0170] A tire of the present disclosure, having a tread made of the aforementioned rubber composition, can be manufactured by conventional methods. That is, an unvulcanized rubber composition, in which the above components are blended with the rubber component as needed, is extruded to match the shape of at least one rubber layer constituting the tread, bonded together with other tire components on a tire molding machine, and molded in a conventional method to form an unvulcanized tire. This unvulcanized tire is then heated and pressurized in a vulcanizing machine to manufacture the tire. The vulcanization conditions are not particularly limited, and for example, a method of vulcanization at 150 to 200°C for 10 to 30 minutes can be cited.

[0171] <Application> The tires disclosed herein can be general-purpose tires such as passenger car tires, truck / bus tires, and motorcycle tires, or racing tires. Passenger car tires refer to tires intended for use on four-wheeled vehicles with a maximum load capacity of 1000 kg or less. Furthermore, the tires disclosed herein can be used as all-season tires, summer tires, and winter tires such as studless tires. [Examples]

[0172] The following examples (implementations) are considered preferable for implementation, but the scope of this disclosure is not limited to these examples.

[0173] Assuming a tire having a tread made of rubber compositions obtained according to Tables 1-4 using the various chemicals listed below, the results calculated based on the evaluation method described below are shown in Tables 1-4.

[0174] The various chemicals used in the examples and comparative examples are summarized below. SBR1: HP755 manufactured by Asahi Kasei Corporation (S-SBR, styrene content: 39.5% by mass, vinyl content: 38.2 mol%, oil content: 37.5 parts by weight per 100 parts by weight of rubber component) SBR2: JSR1723 manufactured by JSR Corporation (E-SBR, styrene content: 24% by mass, vinyl content: 17 mol%, Mw: 480,000, contains 37.5 parts by weight of oil per 100 parts by weight of rubber component) SBR3: HPR840 manufactured by JSR Corporation (S-SBR, styrene content: 10% by mass, vinyl content: 42 mol%, Mw: 190,000, non-oil-based product) NR:TSR20 BR: UBEPOL BR (registered trademark) 150B (cis content: 97 mol%) manufactured by Ube Industries, Ltd. Carbon Black 1: Seast 9 (N2SA: 142m) manufactured by Tokai Carbon Co., Ltd. 2 / g, DBP oil absorption: 115mL / 100g, average primary particle size: 19nm) Carbon Black 2: Show Black N330 (N2SA: 75m) manufactured by Cabot Japan Co., Ltd. 2 / g, DBP oil absorption: 102mL / 100g, average primary particle size: 28nm) Silica 1: Silica 1: ULTRASIL (registered trademark) VN3 (N2SA: 175m) manufactured by Evonik Degussa. 2 / g, average primary particle diameter: 17nm) Silica 2: Evonik Degussa's UltraSil 9100GR (N2SA: 230m 2 / g, average primary particle diameter: 15nm) Silane coupling agent: Si69 (bis(3-triethoxysilylpropyl)tetrasulfide) manufactured by Evonik Degussa. Resin component 1: Sylvatraxx 4401 manufactured by Kraton (a copolymer of α-methylstyrene and styrene, softening point: 85°C) Resin component 2: Coresin manufactured by BASF (pt-butylphenol acetylene resin (condensation resin of pt-butylphenol and acetylene), softening point: 145°C) Ester-based plasticizer: DOS (bis(2-ethylhexyl) sebacate) manufactured by Oyagi Chemical Industry Co., Ltd. Liquid rubber 1: L-SBR-820 (liquid SBR) manufactured by Kuraray Co., Ltd. Liquid rubber 2: RICON 134 (Liquid BR) manufactured by Cray Valley Oil: VivaTec500 (TDAE oil) manufactured by H&R Co., Ltd. Zinc oxide: Two types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: Beads of stearic acid manufactured by NOF Corporation Anti-aging agent: Antigen 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd. Wax: Sunnock N manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Sulfur: Powdered sulfur manufactured by Karuizawa Sulfur Co., Ltd. Vulcanization accelerator 1: Noxellar DM-P (di-2-benzothiazolyl disulfide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 2: Sancella NS-G (Nt-butyl-2-benzothiazole sulfenamide) from Sanshin Chemical Industry Co., Ltd. Vulcanization accelerator 3: Soxinol DG (1,3-diphenylguanidine) manufactured by Sumitomo Chemical Co., Ltd.

[0175] (Examples and Comparative Examples) According to the formulations shown in Tables 1 to 4, the chemicals other than sulfur and vulcanization accelerator are mixed in a 1.7 L sealed Banbury mixer for 1 to 10 minutes until the discharge temperature reaches 150 to 160°C to obtain a mixture. Next, using a twin-screw open roll mixer, sulfur and vulcanization accelerator are added to the mixture and mixed for 4 minutes until the temperature reaches 105°C to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition is extruded using an extruder equipped with a die of a predetermined shape to form a tread shape having a land ratio R as shown in Tables 1 to 4, and bonded together with other tire components to produce an unvulcanized tire. Each test tire (for competition tires in Tables 1 and 2, size: 205 / 65R15, rim: 15×7.0JJ, internal pressure: 230kPa; for passenger car tires in Tables 3 and 4, size: 215 / 60R16, rim: 16×6.5JJ, internal pressure: 230kPa) is obtained by press vulcanization at 170°C for 12 minutes.

[0176] The test tire treads of the competition tires shown in Tables 1 and 2 are provided with blocks and recesses, and the ratio of block volume to recess volume is 0.14.

[0177] <Measurement of Tg1 of rubber composition> Each rubber test piece after vulcanization is prepared by cutting a piece from the tread of each test tire, with dimensions of 20 mm in length, 4 mm in width, and 1 mm in thickness, such that the tire circumference is the longer side and the tire radius is the thickness direction. Using a GABO Iplexer series, the tanδ temperature distribution curve is measured under conditions of frequency 10 Hz, initial strain 10%, amplitude ±0.5%, and heating rate 2 °C / min. The tanδ peak temperature corresponding to the largest tanδ value in the measured temperature distribution curve is defined as the glass transition point (Tg1) before acetone extraction.

[0178] <Measurement of Tg2 of rubber composition> Each rubber test piece, after measuring Tg1, is immersed in acetone for 72 hours to extract soluble components. For the extracted rubber test pieces, the tanδ temperature distribution curve is measured using a GABO Iplexer series under the conditions of a frequency of 10 Hz, initial strain of 10%, amplitude of ±0.5%, and heating rate of 2°C / min. The tanδ peak temperature corresponding to the largest tanδ value in the measured temperature distribution curve is defined as the glass transition point (Tg2) after acetone extraction.

[0179] <Measurement of sulfur content (S) in rubber components> Each rubber test piece after vulcanization is prepared by cutting a piece from the tread of each test tire, with dimensions of 20 mm in length, 4 mm in width, and 1 mm in thickness, such that the tire circumference is the longer side and the tire radius is the thickness direction. The amount of sulfur S (mass%) in the test piece is calculated using the oxygen combustion flask method in accordance with JIS K 6233.

[0180] <Measurement of rubber hardness> A hardness measurement sample is prepared by cutting a piece from the tread of each test tire, with the tire circumference being the longer side and the tire radius being the thickness direction, resulting in a length of 20 mm, width of 4 mm, and thickness of 1 mm. For the hardness measurement sample, a Type A durometer is pressed against the sample from the contact surface side of the tread, in accordance with JIS K 6253, and the rubber hardness at 25°C is measured.

[0181] <Measurement of tanδ at 0℃> Each rubber test specimen after vulcanization is prepared by cutting out a piece from each rubber layer of the tread of each test tire, with dimensions of 20 mm in length, 4 mm in width, and 1 mm in thickness, such that the longer side is in the circumferential direction of the tire and the thickness is in the radial direction of the tire. For each rubber test specimen, the loss tangent (tanδ) is measured using a GABO Iplexer series under the conditions of 0°C, 10 Hz, 10% initial strain, and 2.5% dynamic strain.

[0182] <Measurement of tanδ at 100℃> Each vulcanized rubber test piece is prepared by cutting out a piece from each rubber layer of the tread of each test tire, with dimensions of 20 mm in length, 4 mm in width, and 1 mm in thickness, such that the longer side is in the circumferential direction of the tire and the thickness is in the radial direction of the tire. For each rubber test piece, the loss tangent (tanδ) is measured using a GABO Iplexer series under the conditions of a temperature of 100°C, a frequency of 10 Hz, an initial strain of 10%, and a dynamic strain of 2.5%.

[0183] <Measurement of tanδ and E* at 30°C> Each rubber test specimen after vulcanization is prepared by cutting out a piece from each rubber layer of the tread of each test tire, with dimensions of 20 mm in length, 4 mm in width, and 1 mm in thickness, such that the tire circumference is the longer side and the tire radius is the thickness direction. For each rubber test specimen, tanδ and complex modulus (E*) are measured using a GABO iplexer series under conditions of 30°C, 10 Hz, 5% initial strain, and 1% dynamic strain. 30 ) Measure.

[0184] <Peak Grip Performance> Test tires are mounted on all wheels of a domestic FR car (2000cc), and the vehicle is driven 10 times on a dry asphalt test course. During this test, test drivers subjectively evaluate the stability of steering control during the best lap. The evaluation is given as an integer value from 1 to 5 points, with higher scores indicating better steering control stability. The total scores of 20 test drivers are calculated. The total scores of the benchmark comparison (Comparative Example 1 in Tables 1 and 2, Comparative Example 10 in Tables 3 and 4) are converted to a baseline value (100), and the evaluation results of each test tire are indexed and displayed in proportion to the total score. A higher number indicates better grip performance during driving and better peak grip performance at high speeds.

[0185] [Table 1]

[0186] [Table 2]

[0187] [Table 3]

[0188] [Table 4]

[0189] <Embodiment> Examples of embodiments of this disclosure are shown below.

[0190] [1] A tire having a tread section, The tread portion is made of a rubber composition containing rubber components and fillers. The rubber composition contains more than 100 parts by mass of filler per 100 parts by mass of rubber component, The glass transition temperature Tg2 (°C) of the rubber composition after acetone extraction is less than -45. A tire in which Tg2 and R satisfy the following formula (1), where R (%) is the land ratio at the contact surface of the tread portion. (10-1.25Tg2) / R>1.00···(1) [2] The tire according to [1] above, wherein the glass transition temperature Tg1 (°C) of the rubber composition before acetone extraction is -15 or less. [3] The tire according to [1] or [2] above, wherein the amount of sulfur S (mass%) in the rubber component of the rubber composition is 0.95 or less. [4] The tire according to any one of [1] to [3] above, wherein the rubber composition further contains liquid rubber. [5] A tire as described in any of [1] to [4] above, wherein the Tg2 (°C) is -60 or lower. [6] The tire according to any one of [1] to [5] above, wherein the rubber composition contains more than 5 parts by mass but less than 150 parts by mass of carbon black per 100 parts by mass of rubber component. [7] The tire according to any one of [1] to [6] above, wherein the rubber composition contains silica with an average primary particle size of 18 nm or less. [8] A tire as described in any of [1] to [7] above, wherein the right-hand side of equation (1) is 1.10. [9] The tire according to any one of [1] to [8] above, wherein the rubber hardness of the rubber composition is greater than 62 and less than 75.

[10] The tire according to any one of [1] to [9] above, wherein the tanδ (0°C tanδ) of the rubber composition at 0°C is greater than 0.40.

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

[10] above, wherein the tanδ (30°C tanδ) of the rubber composition at 30°C is greater than 0.20.

[12] The complex modulus of elasticity (E*) of the rubber composition at 30°C 30 A tire as described in any of the above [1] to

[11] , having a pressure of less than 30 MPa.

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

[12] above, wherein the product of tanδ at 100°C and R of the rubber composition is 5.0 or more.

[14] The tire according to any one of [1] to

[13] above, wherein the rubber composition contains silica with an average primary particle size of 16 nm or less.

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

[14] above, wherein the rubber composition contains more than 5 parts by mass of an ester-based plasticizer per 100 parts by mass of the rubber component.

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

[15] above, wherein the rubber composition contains more than 1 part by mass of an organic crosslinking agent per 100 parts by mass of the rubber component.

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

[16] above, wherein the product of Tg2 and S of the rubber composition is -50 or less.

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

[17] above, wherein the rubber composition further contains a resin component with a softening point of 90°C or lower.

[19] A tire used for competition, as described in any of the above [1] to

[18] . [Explanation of symbols]

[0191] 1. Tread surface 2. Center Track and Field Club 3 Shoulder Track and Field Club 4 Circumferential groove 5, 6, 7, 8 Width groove 9. Grooves that connect to circumferential grooves at both ends. 10 Circumferential inclined groove 11 Width direction inclined groove 12 blocks 13 recesses C Tire circumferential direction W (Tire width direction) CL tire centerline Te tread edge

Claims

1. A tire having a tread section, The tread portion is made of a rubber composition containing rubber components and fillers. The rubber composition contains more than 100 parts by mass of filler per 100 parts by mass of rubber component, Glass transition temperature Tg after acetone extraction of the rubber composition 2 (°C) is less than -45, When the land ratio at the contact surface of the tread portion is R (%), Tg 2 A tire in which R satisfies the following equation (1). (10-1.25Tg 2 ) / R>1.00・・・(1)

2. Glass transition temperature Tg of the rubber composition before acetone extraction 1 The tire according to claim 1, wherein the temperature (°C) is -15 or lower.

3. The tire according to claim 1 or 2, wherein the amount of sulfur S (mass%) in the rubber component of the rubber composition is 0.95 or less.

4. The tire according to claim 1 or 2, wherein the rubber composition further contains liquid rubber.

5. Tg 2 A tire according to claim 1 or 2, wherein the temperature (°C) is -60 or lower.

6. The tire according to claim 1 or 2, wherein the rubber composition contains more than 5 parts by mass but less than 150 parts by mass of carbon black per 100 parts by mass of rubber component.

7. The tire according to claim 1 or 2, wherein the rubber composition contains silica with an average primary particle size of 18 nm or less.

8. The tire according to claim 1 or 2, wherein the right-hand side of equation (1) is 1.

10.

9. The tire according to claim 1 or 2, wherein the rubber hardness of the rubber composition is greater than 62 and less than 75.

10. The tire according to claim 1 or 2, wherein the tanδ (0°C tanδ) of the rubber composition at 0°C is greater than 0.

40.

11. The tire according to claim 1 or 2, wherein the tanδ (30°C tanδ) of the rubber composition at 30°C is greater than 0.

20.

12. The complex modulus (E*) of the rubber composition at 30°C 30 The tire according to claim 1 or 2, wherein the pressure is less than 30 MPa.

13. The tire according to claim 1 or 2, wherein the product of the rubber composition's 100°C tanδ and R is 5.0 or greater.

14. The tire according to claim 1 or 2, wherein the rubber composition contains silica with an average primary particle diameter of 16 nm or less.

15. The tire according to claim 1 or 2, wherein the rubber composition contains more than 5 parts by mass of an ester-based plasticizer per 100 parts by mass of rubber component.

16. The tire according to claim 1 or 2, wherein the rubber composition contains more than 1 part by mass of an organic crosslinking agent per 100 parts by mass of the rubber component.

17. Tg of the rubber composition 2 The tire according to claim 1 or 2, wherein the product of and S is -50 or less.

18. The tire according to claim 1 or 2, wherein the rubber composition further contains a resin component with a softening point of 90°C or lower.

19. The tire according to claim 1 or 2, which is a racing tire.

Images