Pneumatic tire

Abstract

Provided is a pneumatic tire that improves handling stability during high-speed travel while maintaining good ride comfort. The pneumatic tire has a tread portion (2). The crown belt cord (12) of the crown belt layer (9) is a mixed cord obtained by twisting a first monofilament (16) and a second monofilament (17). In a region inside the tire radial direction of the first circumferential groove (10), the maximum thickness (t1) of the tire radial direction outside the adhesive rubber (13) of the crown belt cord (12) is 1.0 mm or less. The minimum distance (d1) from the groove bottom of the first circumferential groove (10) to the outer surface of the tire radial direction of the crown belt layer (9) is 2.0 mm or less. The tire normal direction distance (d2) from the groove edge (10e) of the first circumferential groove (10) to the outer surface of the crown belt layer (9) is 15.0 mm or less.

Description

Technical Field

[0001] The present disclosure relates to pneumatic tires. Background Art

[0002] Patent Document 1 below proposes a pneumatic tire having a band ply disposed in a tread portion. The band cord of the band ply is a hybrid cord obtained by twisting a nylon fiber tow and an aramid fiber tow.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-154075 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] As described above, pneumatic tires using a hybrid band cord made of materials with different elastic moduli can be expected to improve ride comfort and handling stability. On the other hand, in recent years, with the improvement of vehicle performance, pneumatic tires are required to further improve handling stability during high-speed driving.

[0008] The present disclosure has been made in view of the above circumstances, and a main object of the present disclosure is to provide a pneumatic tire that improves handling stability during high-speed running while maintaining good ride comfort.

[0009] Means for solving problems

[0010] A pneumatic tire disclosed herein includes a tread portion, wherein the tread portion includes a tread rubber constituting a ground contact surface and a cap ply disposed radially inward of the tread rubber. The tread rubber is provided with a first circumferential groove extending continuously in the tire circumferential direction on the ground contact surface. The cap ply includes a band cord disposed substantially parallel to the tire circumferential direction and a topping rubber covering the band cord. The band cord is a hybrid cord formed by twisting a first monofilament with a second monofilament having a smaller elastic modulus than the first monofilament. In a region radially inward of the first circumferential groove, a maximum thickness t1 of the topping rubber on the radially outward side of the band cord is 1.0 mm or less. A minimum distance d1 from the groove bottom of the first circumferential groove to the radially outer surface of the cap ply is 2.0 mm or less. A distance d2 in the tire normal direction from the groove edge of the first circumferential groove to the radially outer surface of the cap ply is 15.0 mm or less.

[0011] Effects of the Invention

[0012] The pneumatic tire of the present disclosure, by adopting the above-described structure, can improve handling stability during high-speed running while maintaining good ride comfort. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 1 is a meridian cross-sectional view of a tire according to one embodiment of the present disclosure.

[0014] Figure 2 yes Figure 1 An enlarged perspective view of the band ply.

[0015] Figure 3 yes Figure 2 An enlarged perspective view of the cap cord.

[0016] Figure 4 yes Figure 1 An enlarged cross-sectional view of the first circumferential groove and the cap layer. DETAILED DESCRIPTION

[0017] Hereinafter, one embodiment of the present disclosure will be described with reference to the accompanying drawings. Figure 1 A meridian cross-sectional view of a pneumatic tire (hereinafter, sometimes simply referred to as a "tire") 1 according to the present embodiment is shown. Figure 1 : is a cross-sectional view of the tire 1 in a normal state including the rotation axis. Figure 1 As shown, the tire 1 of this embodiment is a pneumatic tire for a passenger car. However, the present disclosure is not limited to this embodiment, and can also be applied to heavy-duty tires and motorcycle tires.

[0018] "Normal condition" refers to a tire with a specified specification, assembled on a specified rim, inflated to a specified internal pressure, and unloaded. For tires with unspecified specifications, the "normal condition" refers to a tire not mounted on a vehicle and unloaded, in a standard usage condition consistent with its intended use.

[0019] "Regular rims" are rims whose specifications are determined for each tire within the specification system that includes the tire's specifications. For example, if it is JATMA, it is a "standard rim", if it is TRA, it is a "design rim", and if it is ETRTO, it is a "measuring rim".

[0020] "Normal internal pressure" refers to the air pressure of each specification determined for each tire within the specification system that includes the specifications on which the tire is based. If it is JATMA, it is the "maximum air pressure". If it is TRA, it is the maximum value recorded in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES". If it is ETRTO, it is "INFLATION PRESSURE".

[0021] Unless otherwise specified, the dimensions of various tire components in this specification refer to values ​​measured under the normal conditions. For components within the tire that cannot be measured under normal conditions, the dimensions are measured while maintaining the shape in the normal conditions. Furthermore, unless otherwise specified, the composition of various tire components in this specification refers to the composition of materials taken from new, unused tires. The method for such taking should be such that the composition is minimized.

[0022] The tire 1 of this embodiment includes a carcass 6. The carcass 6 is composed, for example, of a single carcass ply 6A. The carcass ply 6A includes a plurality of carcass cords and a topping rubber covering the plurality of carcass cords. The carcass cords are arranged, for example, at an angle of 75° to 90° relative to the tire circumferential direction. The term "75° to 90°" means "75° to 90°," and this applies throughout this specification. The carcass cords are preferably made of organic fiber cords such as nylon, polyester, or rayon.

[0023] The carcass ply 6A includes a main body portion 6a and a turnback portion 6b. The main body portion 6a extends from one bead portion 4 through one sidewall portion 3, the tread portion 2, the other sidewall portion 3, and the other bead portion 4. The turnback portion 6b is connected to the main body portion 6a and is turned back around the bead core 5 from the axially inner side to the outer side of the tire and extends radially outward.

[0024] The tread portion 2 of this embodiment is provided with a belt layer 8. The belt layer 8 comprises, for example, two belt plies 8A and 8B. Each belt ply 8A and 8B comprises, for example, a plurality of belt cords arranged obliquely with respect to the tire circumferential direction and a topping rubber covering the plurality of belt cords. Each belt cord is preferably inclined at an angle of 10° to 45° with respect to the tire circumferential direction.

[0025] The tread portion 2 includes a tread rubber 2G constituting a contact patch and a cap layer 9 arranged on the inner side of the tread rubber 2G in the radial direction of the tire. The tread rubber 2G is provided with at least one first circumferential groove 10 extending continuously along the circumferential direction of the tire on the contact patch. The tread rubber 2G of this embodiment is provided with three first circumferential grooves 10. The groove width of the first circumferential groove 10 is, for example, 3 mm to 15 mm. The depth of the first circumferential groove 10 is, for example, 5 mm to 10 mm. However, as long as a certain degree of drainage can be expected when the first circumferential groove 10 is driven on a wet road, the groove width and groove depth are not particularly limited. In addition, the tread rubber 2G may also be provided with a second circumferential groove that is different from the above-mentioned first circumferential groove 10.

[0026] Figure 2 An enlarged perspective view of the band ply 9 is shown. The band ply 9 is composed of, for example, a single band ply 11. The band ply 11 includes a band cord 12 arranged approximately parallel to the tire circumferential direction and a topping rubber 13 covering the band cord 12. The band ply 9 may be composed of, for example, multiple overlapping band plies 11 or multiple band plies 11 arranged axially apart from each other. The band ply 11 of this embodiment is, for example, a so-called seamless band formed by winding a single band cord along the tire circumferential direction. In other embodiments, the band ply 11 may include multiple band cords 12 arranged approximately parallel to the tire circumferential direction. The band cords 12 extending approximately parallel to the tire circumferential direction include at least one embodiment in which the band cords 12 extend at an angle of 5° or less relative to the tire circumferential direction.

[0027] Figure 3 FIG. 1 shows an enlarged perspective view of the band cord 12. Figure 3 As shown, the band cord 12 is a hybrid cord formed by twisting a first monofilament 16 with a second monofilament 17 having a lower elastic modulus than the first monofilament 16. The first monofilament 16 and the second monofilament 17 are composed of organic fibers, such as nylon, aramid, PET, and other materials conventionally used for tire cords. Therefore, the band cord 12 of this embodiment appropriately employs a known hybrid cord.

[0028] Figure 4 An enlarged view of the first circumferential groove 10 and the cap layer 9 is shown. Figure 4 In the figure, the belt layer 8 (in the inner side of the tire radial direction of the cap layer 9) is omitted. Figure 1 In addition, Figure 4 In FIG. 1 , the cross section of the band cord 12 is simplified and shown as a circle, but the band cord 12 naturally has the above-mentioned structure. Figure 4As shown, in the present disclosure, in the region radially inward of the first circumferential groove 10, the maximum thickness t1 of the topping rubber 13 radially outward of the band cord 12 is 1.0 mm or less. Furthermore, the minimum distance d1 from the groove bottom of the first circumferential groove 10 to the radially outer surface 9s of the band ply 9 is 2.0 mm or less. Furthermore, the distance d2 in the tire normal direction from the groove edge 10e of the first circumferential groove 10 to the radially outer surface 9s of the band ply 9 is 15.0 mm or less. The outer surface 9s of the band ply 9 refers to the outer surface of the topping rubber 13 covering the band cord 12.

[0029] The tire normal direction refers to a direction perpendicular to the contact surface of the tread portion 2. Furthermore, as used herein, the contact surface of the tread portion 2 refers to the contact surface with a flat surface when a normal load is applied to the tire 1 in a normal state and the tire is in contact with the flat surface at a camber angle of 0°. Furthermore, the groove edge refers to the boundary between the groove opening and the contact surface. The contact surface and groove edge can be imaged using known methods such as CT imaging.

[0030] For pneumatic tires with defined specifications, the "normal load" is determined for each tire within the specification system that includes the tire's specifications. For JATMA, this is the "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 the "LOAD CAPACITY." For tires with undefined specifications, the "normal load" refers to the load acting on a single tire in its standard mounting state. This "standard mounting state" refers to the tire being mounted on a standard vehicle corresponding to the tire's intended use, with the vehicle stationary on a flat road surface in a drivable state.

[0031] The tire 1 of the present disclosure can improve the steering stability during high-speed running while maintaining good ride comfort by adopting the above-mentioned structure. The reason for this is presumably the following mechanism.

[0032] Generally, the cap layer 9 has a significant impact on the degree of vibration absorption of the tread portion 2 and the degree of growth of the outer diameter of the tread portion 2. In other words, the cap layer 9 has a significant impact on the ride comfort during normal driving and the handling stability during high-speed driving. In the present disclosure, the cap cord 12 of the cap layer 9 is a hybrid cord. Therefore, during normal driving with a small outer diameter growth of the tread portion 2, the second monofilament 17 (such as Figure 3In addition, when traveling at high speed, the first monofilament 16 (such as Figure 3 As shown, the same applies hereinafter), the outer diameter growth of the tread portion 2 is suppressed, thereby exhibiting excellent steering stability.

[0033] The inventors conducted intensive research and discovered that by specifying the thickness of the rubber around the cap ply 9, the steering stability can be further improved, thereby completing the present invention. In the present disclosure, as described above, the thickness t1 is specified to be less than 1.0 mm, the distance d1 is specified to be less than 2.0 mm, and the distance d2 is specified to be less than 15.0 mm. This allows the thickness of the rubber contained in the cap ply 9, which is radially outward of the cap cord 12, to be smaller, thereby reducing the influence of the centrifugal force acting on the tread portion 2 during high-speed driving. As a result, the outer diameter growth of the tread portion 2 is suppressed, and the tread profile can be maintained even during high-speed driving, thereby improving the ground contact of the tread portion 2. In the present disclosure, through the above-mentioned mechanism, it is believed that the steering stability during high-speed driving can be improved while maintaining good ride comfort.

[0034] The following describes the structure of this embodiment in more detail. Furthermore, each of the structures described below represents a specific embodiment of this embodiment. Therefore, even without the structures described below, the present disclosure can still achieve the aforementioned effects. Furthermore, even when a tire of the present disclosure having the aforementioned features is individually applied to any one of the structures described below, it is expected that the performance corresponding to each structure will be improved. Furthermore, when multiple structures described below are applied in combination, it is also expected that the performance corresponding to the combination of the structures will be improved.

[0035] like Figure 3 As shown, the band cord 12 of this embodiment has a multi-twisted structure comprising a first cord 18 twisted with a first monofilament 16 and a second cord 19 twisted with a second monofilament 17. However, the band cord 12 is not limited to this structure and may also have a single-twisted structure comprising the first monofilament 16 and the second monofilament 17.

[0036] The difference in elastic modulus between the first monofilament 16 and the second monofilament 17 can be determined, for example, by the tensile strength specified in JIS L1017. The conditions for measuring the tensile strength are not particularly limited, as long as the tensile strength of the first monofilament 16 and the tensile strength of the second monofilament 17 are measured under the same conditions.

[0037] The total fineness of one band cord 12 is, for example, 4400 dtex or less, preferably 2000 dtex to 4000 dtex, and more preferably 2500 dtex to 3500 dtex. Such a band cord 12 contributes to a balanced improvement in ride comfort and steering stability.

[0038] The stress σ1 of the band cord 12 at 3% elongation is, for example, 0.030 (N / tex) or less. This stress σ1 is preferably 0.005 (N / tex) or more, more preferably 0.010 (N / tex) or more, and preferably 0.025 (N / tex) or less, more preferably 0.020 (N / tex) or less. Such a band cord 12 can maintain the durability of the tread portion 2 while providing excellent ride comfort.

[0039] The stress σ2 of the band cord 12 at 5% elongation is, for example, 0.04 (N / tex) or greater. This stress σ2 is preferably 0.043 (N / tex) or greater, more preferably 0.045 (N / tex) or greater, and preferably 0.06 (N / tex) or less, more preferably 0.055 (N / tex) or less. Such a band cord 12 contributes to a balanced improvement in ride comfort and handling stability during high-speed driving.

[0040] The ratio σ1 / σ2 (%) of the stress σ1 to the stress σ2 is preferably 25% or more, more preferably 29% or more, and preferably 50% or less, more preferably 43% or less.

[0041] The stress σ1 and the stress σ2 are measured, for example, by a method for measuring a load at a constant tension specified in JIS L1017.

[0042] like Figure 1 As shown, the tread rubber 2G is provided with a plurality of first circumferential grooves 10. Furthermore, the tread rubber 2G is provided with a plurality of transverse grooves (not shown) extending axially along the tire's contact patch. To balance ride comfort and handling stability, the groove area ratio of the contact patch of the tread portion 2 is preferably 15% or greater, more preferably 20% or greater, preferably 50% or less, more preferably 40% or less, and even more preferably 30% or less. The groove area ratio is the ratio of the sum of the opening areas of all grooves to the total area of ​​a hypothetical contact patch, assuming all grooves on the contact patch of the tread rubber 2G are filled.

[0043] The ratio σ1 / σ2 (%) of the stress σ1 (N / tex) of the band cord 12 at 3% elongation to the stress σ2 (N / tex) of the band cord 12 at 5% elongation is preferably greater than the groove area ratio (%) of the ground contact surface of the tread portion. Specifically, the ratio σ1 / σ2 (%) is preferably 1.50 times or greater, more preferably 1.90 times or greater, and preferably 3.00 times or less, more preferably 2.86 times or less of the groove area ratio (%). This optimizes the ratio σ1 / σ2, achieving excellent steering stability during both low- and medium-speed and high-speed driving.

[0044] The tread rubber 2G contains, for example, a rubber composition having a complex elastic modulus E*1 at 30°C of 10 to 20 (MPa). The complex elastic modulus E*1 is more preferably 12 to 18 (MPa). On the other hand, in the case of a tire that emphasizes ride comfort, the complex elastic modulus E*1 of the tread rubber 2G at 30°C may also be set to 10 (MPa) or less. In addition, the complex elastic modulus E*1 is a value measured in accordance with the standard of JIS-K6394 using the conditions shown below using a "viscoelasticity spectrometer" manufactured by Iwamoto Manufacturing Co., Ltd. The test sample during the measurement is, for example, a rubber sheet obtained from the tread rubber 2G with the tire circumferential direction as the long side, the tire axial direction as the short side, and the tire radial direction as the thickness. The size of the rubber sheet is, for example, 20 mm long side × 4 mm short side × 1 mm thickness.

[0045] Initial strain: 10%

[0046] Amplitude: ±1%

[0047] Frequency: 8Hz

[0048] Deformation Mode: Stretch

[0049] Measurement temperature: 30°C

[0050] The inventors conducted various experiments and discovered that determining the complex elastic modulus E*1 of the tread rubber 2G based on the groove area ratio can help achieve a balanced balance between ride comfort and handling stability. Specifically, the product of the complex elastic modulus E*1 (MPa) and the groove area ratio (%) is preferably 3.0 (MPa) or greater, more preferably 4.3 (MPa) or greater, and preferably 9.0 (MPa) or less, more preferably 7.5 (MPa) or less. This optimizes the deformation of the tread portion 2 during driving, resulting in a balanced improvement in ride comfort and handling stability.

[0051] Furthermore, the product σ2·E*1 (the stress σ2 (N / tex) at 5% elongation of the band cord and the complex elastic modulus E*1 (MPa)) is preferably 0.45 (N·MPa / tex) or greater, more preferably 0.60 (N·MPa / tex) or greater, and preferably 1.05 (N·MPa / tex) or less, more preferably 0.90 (N·MPa / tex) or less. This optimizes the deformation of the tread portion 2 and the band ply 9 during high-speed driving, improving both ride comfort and handling stability in a balanced manner.

[0052] like Figure 4 As shown, the thickness t1 is preferably 0.05 mm or more, more preferably 0.10 mm or more, and preferably 0.50 mm or less, more preferably 0.30 mm or less. This ensures the durability of the cap layer and exhibits the above-mentioned effects.

[0053] The distance d1 is preferably 0.5 mm or more, more preferably 1.0 mm or more, and preferably 1.8 mm or less, more preferably 1.5 mm or less. Thus, the thickness of the rubber at the groove bottom of the first circumferential groove 10 is optimized, thereby more reliably exerting the above-mentioned effect.

[0054] The distance d2 is preferably 5.0 mm or more, more preferably 7.0 mm or more, and preferably 12.0 mm or less, more preferably 10.0 mm or less. Thus, the thickness of the tread rubber 2G is optimized.

[0055] The inventors have discovered that this effect can be further enhanced by determining the stress σ1 of the band cord 12 at 3% elongation in relation to the distance d2. Specifically, the product σ1·d2 of the stress σ1 (N / tex) and the distance d2 (mm) is preferably 0.05 to 0.40 (N·mm / tex), more preferably 0.08 to 0.18. This optimizes the deformation of the tread portion 2 during low and medium speed driving, further improving ride comfort.

[0056] Similarly, it is found that determining the stress σ2 of the band cord 12 at 5% elongation in relation to the distance d2 further improves steering stability. Specifically, the product σ2·d2 (stress σ2 (N / tex) and distance d2 (mm)) is preferably 0.30 to 0.60 (N·mm / tex), and more preferably 0.35 to 0.50. This optimizes the deformation of the tread portion 2 during high-speed driving, further improving steering stability during high-speed driving.

[0057] The ratio t1 / d1 (%) of the thickness t1 to the distance d1 is preferably 5% or greater, more preferably 6.7% or greater, preferably 46.2% or less, and more preferably 30.8% or less. Furthermore, the ratio t1 / d1 (%) of the thickness t1 to the distance d1 is preferably smaller than the groove area ratio (%). Specifically, the ratio t1 / d1 (%) is preferably 0.15 times or greater, more preferably 0.26 times or greater, and preferably 0.77 times or less, and more preferably 0.67 times or less of the groove area ratio (%). This optimizes the thickness t1, maintains the durability of the cap ply 9, and improves ride comfort.

[0058] Furthermore, it can be seen that the distance d1 and the complex elastic modulus E*1 significantly influence ride comfort and handling stability. To achieve a balanced improvement in these properties, it is preferable to regulate the distance d1 and the complex elastic modulus E*1 in a correlated manner. Specifically, the product of the distance d1 (mm) and the complex elastic modulus E*1 (MPa) is preferably 12.0 (MPa·mm) or greater, more preferably 15.0 (MPa·mm) or greater, and preferably 30.0 (MPa·mm) or less, more preferably 22.5 (MPa·mm) or less. This optimizes rubber deformation near the bottom of the first circumferential groove 10, maintaining good ride comfort while improving handling stability during high-speed driving.

[0059] like Figure 1 As shown, the tread rubber 2G of this embodiment is provided with three first circumferential grooves 10, and the above-described structure is established in at least one of the first circumferential grooves 10. In a more preferred embodiment, the above-described structure is established in all of the plurality of first circumferential grooves 10 arranged in the tread rubber 2G. Thus, the above-described effects are reliably achieved.

[0060] As mentioned above, although the particularly preferred embodiment of the present disclosure was described in detail, the present disclosure is not limited to the above-mentioned embodiment, and can be implemented in various modified forms.

[0061] Example

[0062] Based on the specifications of Tables 1 to 4, a pneumatic tire of size 215 / 60R16 that meets the requirements of the present disclosure was trial-produced. As Comparative Example 1, a pneumatic tire was trial-produced in which the cap cord was a hybrid cord and the thickness t1, distance d1, and distance d2 did not meet the requirements of the present disclosure. As Comparative Example 2, a pneumatic tire was trial-produced in which the material of the cap cord was composed only of nylon and the thickness t1, distance d1, and distance d2 did not meet the requirements of the present disclosure. Except for the specifications shown in Tables 1 to 4, the tires of Comparative Examples 1 to 2 have substantially the same structure as the tires of the embodiments. For each test tire, ride comfort and handling stability during high-speed driving were tested. The common specifications and test methods of the test tires are as follows.

[0063] Installed rim: 16×6.5J

[0064] Internal pressure: 210kPa

[0065] Test vehicle displacement: 2000cc

[0066] Drive mode: FF

[0067] Test tire installation position: all wheels

[0068] Ride Comfort

[0069] The ride comfort of the test vehicle while traveling on ordinary roads was evaluated using the following method. Twenty test drivers each took a test ride. Each test driver rated the ride comfort on a scale of 1 to 10 (higher values ​​are better). The total of the 20 scores was calculated. The results were expressed as a score, with the sum of the scores from Comparative Example 1 being 100, with higher values ​​indicating better ride comfort.

[0070] <Handling stability at high speed>

[0071] The handling stability of the test vehicle during high-speed driving was evaluated using the following method. Twenty test drivers each took a test ride. Each test driver rated the handling stability on a scale of 1 to 10 (higher values ​​are better). The total of the 20 scores was calculated. The results were expressed as a score, with the sum of the scores from Comparative Example 1 being 100. Higher values ​​indicate better handling stability during high-speed driving.

[0072] Overall performance

[0073] The overall performance including the ride comfort and high-speed driving stability was evaluated. The result was the sum of the ride comfort score and the high-speed driving stability score, with a larger value indicating better overall performance.

[0074] The test results are shown in Tables 1 to 4.

[0075] [Table 1]

[0076]

[0077] [Table 2]

[0078]

[0079] [Table 3]

[0080]

[0081] [Table 4]

[0082]

[0083] In Tables 1 to 4, a score greater than 96 for ride comfort in Comparative Example 2 indicates that "good ride comfort can be maintained." Furthermore, a score greater than 100 for high-speed handling stability in Comparative Example 1 indicates that the handling stability has improved.

[0084] As a result of the test, it was confirmed that the tires of the examples improved handling stability during high-speed running while maintaining good ride comfort, and that the overall performance including ride comfort and handling stability was improved.

[0085] [Note]

[0086] The present disclosure includes the following aspects.

[0087] [Present Disclosure 1]

[0088] A pneumatic tire having a tread portion, wherein:

[0089] The tread portion includes a tread rubber constituting a ground contact surface and a cap layer disposed radially inward of the tread rubber.

[0090] The tread rubber is provided with a first circumferential groove extending continuously in the tire circumferential direction on the ground contact surface.

[0091] The cap layer includes a band cord arranged substantially parallel to the tire circumferential direction and a topping rubber covering the band cord.

[0092] The band cord is a hybrid cord obtained by twisting a first monofilament and a second monofilament having a smaller elastic modulus than the first monofilament.

[0093] In the region on the inner side of the first circumferential groove in the tire radial direction, the maximum thickness t1 of the topping rubber on the outer side of the band cord in the tire radial direction is 1.0 mm or less.

[0094] The minimum distance d1 from the groove bottom of the first circumferential groove to the outer surface of the cap layer in the tire radial direction is 2.0 mm or less.

[0095] A distance d2 from a groove edge of the first circumferential groove to an outer surface of the cap ply in the tire radial direction in the tire normal direction is 15.0 mm or less.

[0096] [Present Disclosure 2]

[0097] The pneumatic tire according to Disclosure 1, wherein:

[0098] The first monofilament and the second monofilament are composed of organic fibers.

[0099] [Present Disclosure 3]

[0100] The pneumatic tire according to Disclosure 1 or 2, wherein:

[0101] The total fineness of the band cord is 4400 dtex or less.

[0102] [Present Disclosure 4]

[0103] The pneumatic tire according to any one of Disclosures 1 to 3, wherein

[0104] The stress σ1 of the band cord at 3% elongation is 0.03 (N / tex) or less.

[0105] [Present Disclosure 5]

[0106] The pneumatic tire according to Disclosure 4, wherein:

[0107] The product σ1·d2 of the stress σ1 (N / tex) and the distance d2 (mm) is 0.05 to 0.40 (N·mm / tex).

[0108] [Present Disclosure 6]

[0109] The pneumatic tire according to any one of Disclosures 1 to 5, wherein

[0110] The stress σ2 of the band cord at 5% elongation is 0.04 to 0.06 (N / tex).

[0111] [Present Disclosure 7]

[0112] The pneumatic tire according to Disclosure 6, wherein:

[0113] The product σ2·d2 of the stress σ2 (N / tex) and the distance d2 (mm) is 0.30 to 0.60 (N·mm / tex).

[0114] [Present Disclosure 8]

[0115] The pneumatic tire according to any one of Disclosures 1 to 7, wherein

[0116] The groove area ratio of the ground contact surface of the tread portion is 15% to 50%.

[0117] [Present Disclosure 9]

[0118] The pneumatic tire according to Disclosure 8, wherein:

[0119] A ratio t1 / d1 (%) of the thickness t1 to the distance d1 is smaller than the groove area ratio (%).

[0120] [Present Disclosure 10]

[0121] The pneumatic tire according to any one of Disclosures 1 to 9, wherein

[0122] The tread rubber includes a rubber composition having a complex elastic modulus E*1 at 30° C. of 10 (MPa) or less.

[0123] [Present Disclosure 11]

[0124] The pneumatic tire according to Disclosure 10, wherein:

[0125] The product d1·E*1 of the distance d1 (mm) and the complex elastic modulus E*1 (MPa) is 5.0 to 30.0 (MPa·mm).

[0126] [Present Disclosure 12]

[0127] The pneumatic tire according to Disclosure 10 or 11, wherein:

[0128] The product σ2·E*1 of the stress σ2 (N / tex) of the band cord at 5% elongation and the complex elastic modulus E*1 (MPa) is 0.40 to 1.60 (N·MPa / tex).

[0129] [Present Disclosure 13]

[0130] The pneumatic tire according to any one of Disclosures 10 to 12, wherein

[0131] The product of the complex elastic modulus E*1 (MPa) and the groove area ratio (%) of the ground contact surface of the tread portion is 5.0 (MPa) or less.

[0132] [Present Disclosure 14]

[0133] The pneumatic tire according to any one of Disclosures 1 to 13, wherein

[0134] A ratio σ1 / σ2 (%) of the stress σ1 (N / tex) of the band cord at 3% elongation to the stress σ2 (N / tex) of the band cord at 5% elongation is greater than a groove area ratio (%) of the ground contact surface of the tread portion.

[0135] [Present Disclosure 15]

[0136] The pneumatic tire according to any one of Disclosures 1 to 14, wherein

[0137] The thickness t1 is 0.05mm to 0.30mm,

[0138] The distance d1 is 0.5mm to 1.5mm,

[0139] The distance d2 is 5.0 mm to 12.0 mm.

[0140] Description of labels

[0141] 2: tread portion; 2G: tread rubber; 9: cap ply; 10: first circumferential groove; 10e: groove edge; 12: cap cord; 13: topping rubber; 16: first monofilament; 17: second monofilament.

Claims

1. A pneumatic tire having a tread portion, wherein: The tread portion includes a tread rubber constituting a ground contact surface and a cap layer disposed radially inward of the tread rubber. The tread rubber is provided with a first circumferential groove extending continuously in the tire circumferential direction on the ground contact surface. The cap layer includes a band cord arranged substantially parallel to the tire circumferential direction and a topping rubber covering the band cord. The band cord is a hybrid cord obtained by twisting a first monofilament and a second monofilament having a smaller elastic modulus than the first monofilament. In the region on the inner side of the first circumferential groove in the tire radial direction, the maximum thickness t1 of the topping rubber on the outer side of the band cord in the tire radial direction is 1.0 mm or less. The minimum distance d1 from the groove bottom of the first circumferential groove to the outer surface of the cap layer in the tire radial direction is 2.0 mm or less. A distance d2 from the groove edge of the first circumferential groove to the outer surface of the cap ply in the tire radial direction in the tire normal direction is 15.0 mm or less. The groove area ratio of the ground contact surface of the tread portion is 15% to 50%, A ratio t1 / d1 (%) of the thickness t1 to the distance d1 is smaller than the groove area ratio (%).

2. The pneumatic tire according to claim 1, wherein The first monofilament and the second monofilament are composed of organic fibers.

3. The pneumatic tire according to claim 1 or 2, wherein: The total fineness of the band cord is 4400 dtex or less.

4. The pneumatic tire according to claim 1, wherein The stress σ1 of the band cord at 3% elongation is 0.03 (N / tex) or less.

5. The pneumatic tire according to claim 4, wherein The product σ1·d2 of the stress σ1 (N / tex) and the distance d2 (mm) is 0.05 to 0.40 (N·mm / tex).

6. The pneumatic tire according to claim 1, wherein The stress σ2 of the band cord at 5% elongation is 0.04 to 0.06 (N / tex).

7. The pneumatic tire according to claim 6, wherein: The product σ2·d2 of the stress σ2 (N / tex) and the distance d2 (mm) is 0.30 to 0.60 (N·mm / tex).

8. The pneumatic tire according to claim 1, wherein The tread rubber includes a rubber composition having a complex elastic modulus E*1 at 30° C. of 10 (MPa) or less.

9. The pneumatic tire according to claim 8, wherein: The product d1·E*1 of the distance d1 (mm) and the complex elastic modulus E*1 (MPa) is 5.0 to 30.0 (MPa·mm).

10. The pneumatic tire according to claim 8, wherein The product σ2·E*1 of the stress σ2 (N / tex) of the band cord at 5% elongation and the complex elastic modulus E*1 (MPa) is 0.40 to 1.60 (N·MPa / tex).

11. The pneumatic tire according to claim 8, wherein The product of the complex elastic modulus E*1 (MPa) and the groove area ratio (%) of the ground contact surface of the tread portion is 5.0 (MPa) or less.

12. The pneumatic tire according to claim 1, wherein The thickness t1 is 0.05mm to 0.30mm, The distance d1 is 0.5mm to 1.5mm, The distance d2 is 5.0 mm to 12.0 mm.

13. A pneumatic tire having a tread portion, wherein: The tread portion includes a tread rubber constituting a ground contact surface and a cap layer disposed radially inward of the tread rubber. The tread rubber is provided with a first circumferential groove extending continuously in the tire circumferential direction on the ground contact surface. The cap layer includes a band cord arranged substantially parallel to the tire circumferential direction and a topping rubber covering the band cord. The band cord is a hybrid cord obtained by twisting a first monofilament and a second monofilament having a smaller elastic modulus than the first monofilament. In the region on the inner side of the first circumferential groove in the tire radial direction, the maximum thickness t1 of the topping rubber on the outer side of the band cord in the tire radial direction is 1.0 mm or less. The minimum distance d1 from the groove bottom of the first circumferential groove to the outer surface of the cap layer in the tire radial direction is 2.0 mm or less. A distance d2 from the groove edge of the first circumferential groove to the outer surface of the cap ply in the tire radial direction in the tire normal direction is 15.0 mm or less. A ratio σ1 / σ2 (%) of the stress σ1 (N / tex) of the band cord at 3% elongation to the stress σ2 (N / tex) of the band cord at 5% elongation is greater than a groove area ratio (%) of the ground contact surface of the tread portion.

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