pneumatic tires

Abstract

Provided is a pneumatic with which steering stability during high-speed travel is improved while good ride comfort is maintained.　The pneumatic tire has a tread part 2. A band cord 12 of a band layer 9 is a hybrid cord in which first filaments 16 and second filaments 17 are twisted together. In a tire-radially inner region of a first circumferential groove 10, the maximum thickness t1 of topping rubber 13 on the tire-radially outer side of the band cord 12 is 1.0 mm or less. The minimum distance d1 from the bottom of the first circumferential groove 10 to the tire-radially outer surface of the band layer 9 is 2.0 mm or less. The distance d2 in the normal direction of the tire from a groove edge 10e of the first circumferential groove 10 to the outer surface of the band layer 9 is 15.0 mm or less.

Description

Technical Field

[0001] This disclosure relates to pneumatic tires.

Background Art

[0002] In Patent Document 1 below, a pneumatic tire in which a band layer is disposed in a tread portion has been proposed. Further, a hybrid cord in which strands of nylon fiber and strands of aramid fiber are twisted together is adopted for the band cord of the band layer.

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As described above, a pneumatic tire in which a hybrid cord containing materials having different elastic moduli is adopted for the band cord can be expected to improve riding comfort and handling stability. On the other hand, in recent years, with the improvement of vehicle performance, further improvement in handling stability during high-speed driving of pneumatic tires has been required.

[0005] This disclosure has been devised in view of the above actual situation, and the main problem is to provide a pneumatic tire that improves handling stability during high-speed driving while maintaining good riding comfort.

Means for Solving the Problems

[0006] This disclosure relates to a pneumatic tire having a tread portion, wherein the tread portion includes a tread rubber constituting a contact surface and a band 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 from the contact surface, the band layer 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 together a first filament and a second filament having a lower modulus of elasticity than the first filament, the maximum thickness t1 of the topping rubber on the radially outward side of the band cord in the region radially inward of the first circumferential groove is 1.0 mm or less, the minimum distance d1 from the groove bottom of the first circumferential groove to the radially outer surface of the band layer is 2.0 mm or less, and the distance d2 in the tire normal direction from the groove edge of the first circumferential groove to the radially outer surface of the band layer is 15.0 mm or less. [Effects of the Invention]

[0007] By adopting the above configuration, the pneumatic tire of this disclosure can improve handling stability at high speeds while maintaining good ride comfort. [Brief explanation of the drawing]

[0008] [Figure 1] This is a meridional cross-sectional view of a tire according to one embodiment of the present disclosure. [Figure 2] Figure 1 is an enlarged perspective view of the bandply. [Figure 3] Figure 2 is an enlarged perspective view of the bandcode. [Figure 4] Figure 1 is an enlarged cross-sectional view of the first circumferential groove and band layer. [Explanation of Symbols]

[0009] 2 Tread section 2G Tread Rubber 9-band layer 10 First circumferential groove 10e groove edge 12 band chords 13 Topping Rubber 16. First Filament 17. Second filament [Modes for carrying out the invention]

[0010] Hereinafter, one embodiment of the present disclosure will be described with reference to the drawings. Figure 1 shows a meridian cross-sectional view of a pneumatic tire (hereinafter sometimes simply referred to as "tire") 1 of this embodiment. Figure 1 is a cross-sectional view of tire 1 including the axis of rotation in its normal state. As shown in Figure 1, tire 1 of this embodiment is a pneumatic tire for a passenger car. However, the present disclosure is not limited to this embodiment and may also be applied to heavy-duty tires or motorcycle tires.

[0011] "Normal condition" refers to the state in which, for tires with defined specifications, the tire is mounted on a standard rim, filled to the standard internal pressure, and is unloaded. For tires without defined specifications, the normal condition refers to the standard usage condition according to the tire's intended use, meaning the tire is not mounted on a vehicle and is unloaded.

[0012] A "standard rim" is the rim defined for each tire within the standards system that the tire is based on. For example, it is the "standard rim" for JATMA, the "Design Rim" for TRA, and the "Measuring Rim" for ETRTO.

[0013] "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 JATMA, it is the "maximum air pressure," for TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and for ETRTO, it is the "INFLATION PRESSURE."

[0014] In this specification, unless otherwise specified, the dimensions of each part of the tire are values ​​measured under the normal conditions. In the case of internal tire components that cannot be measured while maintaining the normal conditions, their dimensions shall be measured while maintaining the shape of the normal conditions. Furthermore, in this specification, unless otherwise specified, the composition of each part of the tire refers to the composition of materials taken from a new, unused tire. In addition, the sampling method shall be one that minimizes changes to the composition as much as possible.

[0015] The tire 1 of this embodiment has a carcass 6. The carcass 6 is composed of, for example, one carcass ply 6A. The carcass ply 6A includes a plurality of carcass cords and a topping rubber covering them. The carcass cords are arranged, for example, at an angle of 75 to 90° with respect to the circumferential direction of the tire. Note that "75 to 90°" means "75° or more and 90° or less", and the same applies hereafter in this specification. For the carcass cords, for example, organic fiber cords such as nylon, polyester, or rayon are preferably used.

[0016] The carcass ply 6A has a main body portion 6a and a folded 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, to the other bead portion 4. The folded portion 6b is connected to the main body portion 6a and extends radially outward around the bead core 5, folded from the inside in the tire axial direction to the outside.

[0017] The tread portion 2 of this embodiment is provided with a belt layer 8. The belt layer 8 includes, for example, two belt plies 8A and 8B. Each belt ply 8A and 8B includes, for example, a plurality of belt cords arranged at an angle with respect to the circumferential direction of the tire, and a topping rubber covering them. It is desirable that each belt cord is inclined at an angle of 10 to 45° with respect to the circumferential direction of the tire.

[0018] The tread portion 2 includes a tread rubber 2G that forms a ground contact surface, and a band layer 9 disposed on the inner side of the tread rubber 2G in the tire radial direction. The tread rubber 2G is provided with at least one first circumferential groove 10 that continuously extends in the tire circumferential direction on the ground contact surface. In the tread rubber 2G of the present embodiment, three first circumferential grooves 10 are provided. The groove width of the first circumferential groove 10 is, for example, 3 to 15 mm. The depth of the first circumferential groove 10 is, for example, 5 to 10 mm. However, the first circumferential groove 10 is not particularly limited with respect to the groove width and the groove depth as long as it can be expected to have a certain degree of drainage performance during wet running. In addition, a second circumferential groove having a different form from the above-described first circumferential groove 10 may be disposed in the tread rubber 2G.

[0019] FIG. 2 shows an enlarged perspective view of the band layer 9. The band layer 9 is, for example, composed of a single band ply 11. The band ply 11 includes a band cord 12 disposed substantially parallel to the tire circumferential direction, and a topping rubber 13 that covers the band cord 12. The band layer 9 may be formed by, for example, stacking a plurality of band plies 11, or a plurality of band plies 11 may be disposed apart from each other in the tire axial direction. In addition, the band ply 11 of the present embodiment is configured as a so-called jointless band in which, for example, one band cord is wound in the tire circumferential direction. In other embodiments, the band ply 11 may include a plurality of band cords 12 disposed substantially parallel to the tire circumferential direction. Note that the band cord 12 extending substantially parallel to the tire circumferential direction includes at least a mode in which the band cord 12 extends at an angle of 5° or less with respect to the tire circumferential direction.

[0020] Figure 3 shows an enlarged perspective view of the band cord 12. As shown in Figure 3, the band cord 12 is a hybrid cord formed by twisting a first filament 16 and a second filament 17 having a lower elastic modulus than the first filament 16. The first filament 16 and the second filament 17 are made of organic fibers, and for example, those conventionally used as materials for tire cords such as nylon, aramid, PET, etc. are adopted. Thus, a known hybrid cord is appropriately adopted for the band cord 12 of the present embodiment.

[0021] Figure 4 shows an enlarged view of the first circumferential groove 10 and the band layer 9. In Figure 4, the belt layer 8 (shown in Figure 1) arranged on the inner side in the tire radial direction of the band layer 9 is omitted. Also, in Figure 4, the cross-section of the band cord 12 is simplified and shown as a circle, but it is needless to say that the band cord 12 has the above-described configuration. As shown in Figure 4, in the present disclosure, in the region on the inner side in the tire radial direction of the first circumferential groove 10, the maximum thickness t1 of the topping rubber 13 on the outer side in the tire radial direction of the band cord 12 is 1.0 mm or less. Also, the minimum distance d1 from the groove bottom of the first circumferential groove 10 to the outer surface 9s in the tire radial direction of the band layer 9 is 2.0 mm or less. Further, the distance d2 in the tire normal direction from the groove edge 10e of the first circumferential groove 10 to the outer surface 9s in the tire radial direction of the band layer 9 is 15.0 mm or less. Here, the outer surface 9s of the band layer 9 means the outer surface of the topping rubber 13 covering the band cord 12.

[0022] The tire normal direction means the direction perpendicular to the ground contact surface of the tread portion 2. Also, in the specification, the ground contact surface of the tread portion 2 means the contact surface with the plane when the normal load is applied to the tire 1 in the normal state and it is grounded on the plane at a camber angle of 0°. Also, the groove edge means the boundary between the opening region of the groove and the contact surface. The contact surface and the groove edge can be photographed by a known method such as CT imaging.

[0023] "Regular load" refers to the load specified for each tire in the standard system, including the standard on which the tire is based, for pneumatic tires with various standards defined. 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. For tires without various standards defined, "regular load" refers to the load acting on a single tire in its standard mounting condition. The aforementioned "standard mounting condition" refers to a state in which the tire is mounted on a standard vehicle appropriate to the tire's intended use, and the vehicle is stationary on a flat road surface in a drivable state.

[0024] The tire 1 of this disclosure, by adopting the above configuration, can improve handling stability at high speeds while maintaining good ride comfort. The following mechanism is presumed to be the reason for this.

[0025] Generally, the band layer 9 has a significant impact on the degree of vibration absorption of the tread portion 2 and the degree of outer diameter growth of the tread portion 2. In other words, the band layer 9 has a significant impact on ride comfort during normal driving and handling stability during high-speed driving. In this disclosure, a hybrid cord is used for the band cord 12 of the band layer 9. As a result, during normal driving when the outer diameter growth of the tread portion 2 is small, the second filament 17 (shown in Figure 3, and the same applies hereinafter), which has a low modulus of elasticity, becomes dominant, maintaining good ride comfort. Furthermore, during high-speed driving, the first filament 16 (shown in Figure 3, and the same applies hereinafter), which has a high modulus of elasticity, suppresses the outer diameter growth of the tread portion 2, resulting in excellent handling stability.

[0026] As a result of diligent research, the developers discovered that the handling stability could be further improved by specifying the thickness of the rubber around the band layer 9, and thus completed this disclosure. In this disclosure, as described above, the thickness t1 is specified to be 1.0 mm or less, the distance d1 to be 2.0 mm or less, and the distance d2 to be 15.0 mm or less. This makes it possible to set the thickness of the rubber on the radially outer side of the tire to be smaller than the band cord 12 included in the band layer 9, and consequently reduces the effect of centrifugal force acting on the tread portion 2 during high-speed driving. Therefore, the outer diameter growth of the tread portion 2 is suppressed, the tread profile can be maintained even during high-speed driving, and the contact performance of the tread portion 2 is improved. In this disclosure, it is believed that the handling stability at high speeds can be improved while maintaining good ride comfort through the mechanism described above.

[0027] The configuration of this embodiment will be described in more detail below. Note that each configuration described below represents a specific aspect of this embodiment. Therefore, it goes without saying that this disclosure can achieve the above-described effects even without the configurations described below. Furthermore, even if any one of the configurations described below is applied individually to a tire of this disclosure having the above-described features, an improvement in performance corresponding to each configuration can be expected. Moreover, if several of the configurations described below are applied in combination, a combined improvement in performance corresponding to each configuration can be expected.

[0028] As shown in Figure 3, the band cord 12 of this embodiment is composed of a double-twisted structure in which a first yarn 18, formed by twisting together the first filament 16, and a second yarn 19, formed by twisting together the second filament 17. However, the band cord 12 is not limited to this configuration and may also be a single-twisted structure including the first filament 16 and the second filament 17.

[0029] The difference in elastic modulus between the first filament 16 and the second filament 17 shall be determined, for example, by the tensile strength specified in JIS L1017. The measurement conditions for the tensile strength are not particularly limited, and it is sufficient that the tensile strength of the first filament 16 and the tensile strength of the second filament 17 are measured under the same conditions.

[0030] The total fineness of a single band cord 12 is, for example, 4400 dtex or less, preferably 2000-4000 dtex, and more preferably 2500-3500 dtex. Such a band cord 12 helps to improve ride comfort and handling stability in a balanced way.

[0031] The stress σ1 of the band cord 12 when stretched by 3% is, for example, 0.030 (N / tex) or less. Preferably, the stress σ1 is 0.005 (N / tex) or more, more preferably 0.010 (N / tex) or more, preferably 0.025 (N / tex) or less, and more preferably 0.020 (N / tex) or less. Such a band cord 12 can provide excellent ride comfort while maintaining the durability of the tread portion 2.

[0032] The stress σ2 of the band cord 12 when stretched by 5% is, for example, 0.04 (N / tex) or more. Preferably, the stress σ2 is 0.043 (N / tex) or more, more preferably 0.045 (N / tex) or more, preferably 0.06 (N / tex) or less, and more preferably 0.055 (N / tex) or less. Such a band cord 12 helps to improve ride comfort and handling stability at high speeds in a balanced manner.

[0033] The ratio of the stress σ1 to the stress θ2, σ1 / σ2 (%), is preferably 25% or more, more preferably 29% or more, preferably 50% or less, and more preferably 43% or less.

[0034] The stresses σ1 and σ2 mentioned above are measured, for example, by the method for measuring constant elongation load as specified in JIS L1017.

[0035] As shown in Figure 1, the tread rubber 2G has a plurality of first circumferential grooves 10. The tread rubber 2G also has a plurality of lateral grooves extending in the direction of the tire axis along the contact surface (not shown). From the viewpoint of achieving both ride comfort and handling stability, the see-through ratio of the contact surface of the tread portion 2 is preferably 15% or more, more preferably 20% or more, preferably 50% or less, more preferably 40% or less, and even more preferably 30% or less. The see-through ratio is the ratio of the sum of the opening areas of all grooves to the total area of ​​the virtual contact surface when all the grooves arranged on the contact surface of the tread rubber 2G are filled.

[0036] The ratio σ1 / σ2 (%) of the stress σ1 (N / tex) of the band cord 12 when it is stretched 3% to the stress σ2 (N / tex) of the band cord 12 when it is stretched 5% is preferably greater than the shear ratio (%) of the contact surface of the tread portion. Specifically, the ratio σ1 / σ2 (%) is preferably 1.50 times or more, more preferably 1.90 times or more, preferably 3.00 times or less, and more preferably 2.86 times or less of the shear ratio (%). This optimizes the ratio σ1 / σ2, resulting in excellent handling stability at both low-to-medium speed and high-speed driving.

[0037] The tread rubber 2G includes, for example, a rubber composition with a complex modulus of elasticity E*1 of 10 to 20 (MPa) at 30°C. A complex modulus of elasticity E*1 of 12 to 18 (MPa) is more desirable. On the other hand, for tires where ride comfort is important, the complex modulus of elasticity E*1 of the tread rubber 2G may be 10 (MPa) or less at 30°C. The complex modulus of elasticity E*1 is a value measured using a "viscoelastic spectrometer" manufactured by Iwamoto Seisakusho Co., Ltd. under the following conditions, in accordance with the provisions of JIS-K6394. For the test sample used during measurement, for example, a rubber piece obtained from the tread rubber 2G such that the tire circumference is the long side, the tire axial direction is the short side, and the tire radius direction is the thickness is used. The dimensions of the rubber piece are, for example, 20 mm long x 4 mm short x 1 mm thick. Initial distortion: 10% Amplitude: ±1% Frequency: 8Hz Deformation mode: Stretch Measurement temperature: 30℃

[0038] The developers, through various experiments, found that the complex modulus of elasticity E*1 of the tread rubber 2G can be determined according to the shear ratio, thereby contributing to a balance between ride comfort and handling stability. Specifically, the product of the complex modulus of elasticity E*1 (MPa) and the shear ratio (%) is preferably 3.0 (MPa) or higher, more preferably 4.3 (MPa) or higher, preferably 9.0 (MPa) or lower, and more preferably 7.5 (MPa) or lower. This optimizes the amount of deformation of the tread section 2 during driving, and can improve ride comfort and handling stability in a well-balanced manner.

[0039] Furthermore, the product σ2·E*1 of the stress σ2 (N / tex) of the band cord when it is elongated by 5% and the complex modulus E*1 (MPa) is, For example, 0.40 (N·MPa / tex) or higher, Preferably 0.45 (N·MPa / tex) or higher, more preferably 0.60 (N·MPa / tex) or higher. For example, 1.60 (N·MPa / tex) or less, Ideally, the pressure should be 1.05 (N·MPa / tex) or less, and more preferably 0.90 (N·MPa / tex) or less. This optimizes the deformation of the tread section 2 and band layer 9 during high-speed driving, resulting in a well-balanced improvement in ride comfort and handling stability.

[0040] As shown in Figure 4, the thickness t1 is preferably 0.05 mm or more, more preferably 0.10 mm or more, preferably 0.50 mm or less, and more preferably 0.30 mm or less. This ensures the durability of the band layer while achieving the effects described above.

[0041] The aforementioned distance d1 is preferably 0.5 mm or more, more preferably 1.0 mm or more, preferably 1.8 mm or less, and more preferably 1.5 mm or less. This optimizes the thickness of the rubber at the bottom of the first circumferential groove 10, and the above-mentioned effects are more reliably achieved.

[0042] The aforementioned distance d2 is preferably 5.0 mm or more, more preferably 7.0 mm or more, preferably 12.0 mm or less, and more preferably 10.0 mm or less. This optimizes the thickness of the tread rubber 2G.

[0043] The developers found that the above-mentioned effects can be further improved by relating the stress σ1 of the band cord 12 when it is stretched by 3% 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), and more preferably 0.08 to 0.18. This optimizes the amount of deformation of the tread portion 2 during medium to low speed driving, which can further improve ride comfort.

[0044] Similarly, it was found that the handling stability is further improved by relating the stress σ2 when the band cord 12 is stretched by 5% with the distance d2. Specifically, the product σ2·d2 of the stress σ2 (N / tex) and the distance d2 (mm) is preferably 0.30 to 0.60 (N·mm / tex), and more preferably 0.35 to 0.50. This optimizes the amount of deformation of the tread section 2 during high-speed driving, further improving handling stability during high-speed driving.

[0045] The ratio t1 / d1(%) of the thickness t1 to the distance d1 is preferably 5% or more, more preferably 6.7% or more, 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 shear ratio(%). Specifically, the ratio t1 / d1(%) is preferably 0.15 times or more, more preferably 0.26 times or more, preferably 0.77 times or less, and more preferably 0.67 times or less of the shear ratio(%). This optimizes the thickness t1, maintaining the durability of the band layer 9 while improving ride comfort.

[0046] Furthermore, it was found that the distance d1 and the complex modulus of elasticity E*1 have a significant impact on ride comfort and handling stability, and that in order to improve these performances in a balanced manner, it is desirable to define the distance d1 and the complex modulus of elasticity E*1 in relation to each other. Specifically, the product of the distance d1 (mm) and the complex modulus of elasticity E*1 (MPa) d1·E*1 teeth, For example, 5.0 (MPa·mm) or more, Preferably, it is 12.0 MPa·mm or higher, more preferably 15.0 MPa·mm or higher, preferably 30.0 MPa·mm or lower, and more preferably 22.5 MPa·mm or lower. This optimizes the deformation of the rubber near the bottom of the first circumferential groove 10, improving handling stability at high speeds while maintaining good ride comfort.

[0047] As shown in Figure 1, the tread rubber 2G of this embodiment is provided with three first circumferential grooves 10, and the above configuration is met in at least one of the first circumferential grooves 10. In a more desirable embodiment, the above configuration is met in all of the multiple first circumferential grooves 10 arranged in the tread rubber 2G. This ensures that the above effects are reliably achieved.

[0048] Although particularly preferred embodiments of this disclosure have been described in detail above, this disclosure is not limited to the embodiments described above and can be implemented in various modified forms. [Examples]

[0049] A pneumatic tire of size 215 / 60R16 that satisfies the requirements of this disclosure was prototyped based on the specifications in Tables 1 to 4. As Comparative Example 1, a pneumatic tire was prototyped in which the band cord was a hybrid cord and did not satisfy the requirements of this disclosure in terms of thickness t1, distance d1, and distance d2. As Comparative Example 2, a pneumatic tire was prototyped in which the band cord material was made solely of nylon and did not satisfy the requirements of this disclosure in terms of thickness t1, distance d1, and distance d2. Except for the specifications shown in Tables 1 to 4, the tires of Comparative Examples 1 and 2 have substantially the same configuration as the tires of the examples. Ride comfort and handling stability at high speeds were tested for each test tire. The common specifications of the test tires and the test methods are as follows. Mounted rim: 16×6.5J Internal pressure: 210kPa Engine displacement of the test vehicle: 2000cc Drive system: FF Test tire mounting position: All wheels

[0050] <Ride comfort> The ride comfort of the above test vehicle when driven on public roads was evaluated using the following method. Twenty test drivers each conducted a test drive, and each test driver scored the ride comfort on a scale of 1 to 10 (higher numbers indicate better performance). The sum of the scores from all 20 drivers was calculated. The results are shown as a score where the sum of the scores for Comparative Example 1 is set to 100, and a higher number indicates better ride comfort.

[0051] <Handling stability at high speeds> The handling stability of the above test vehicle at high speeds was evaluated using the following method. Twenty test drivers each conducted a test drive, and each test driver scored the handling stability on a scale of 1 to 10 (higher numbers indicate better performance). The sum of the scores from all 20 drivers was calculated. The results are shown as a score where the sum of the scores for Comparative Example 1 is set to 100, and a higher number indicates better handling stability at high speeds.

[0052] <Overall Performance> The overall performance, including the ride comfort and handling stability at high speeds, was evaluated. The result is the sum of the scores for ride comfort and handling stability at high speeds; a higher number indicates better overall performance. The test results are shown in Tables 1-4.

[0053] [Table 1]

[0054] [Table 2]

[0055] [Table 3]

[0056] [Table 4]

[0057] In Tables 1-4, a score higher than 96 for Comparative Example 2 indicates that "good ride comfort is maintained." Furthermore, a score higher than 100 for Comparative Example 1 indicates that the handling stability at high speeds has improved.

[0058] The test results showed that the tires in the example improved handling stability at high speeds while maintaining good ride comfort, confirming an overall improvement in performance, including ride comfort and handling stability.

[0059] [Note] This disclosure includes the following aspects:

[0060] [Disclosure 1] A pneumatic tire having a tread section, The tread portion includes a tread rubber that constitutes the contact surface and a band layer arranged on the radially inward side of the tread rubber. The tread rubber is provided with a first circumferential groove that extends continuously in the tire circumferential direction along the contact surface. The band layer includes band cords arranged substantially parallel to the circumferential direction of the tire, and a topping rubber covering the band cords. The aforementioned band cord is a hybrid cord formed by twisting together a first filament and a second filament having a lower modulus of elasticity than the first filament. In the region of the first circumferential groove on the radially inner side of the tire, the maximum thickness t1 of the topping rubber on the radially outer side of the band cord 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 band layer in the tire radial direction is 2.0 mm or less. The distance d2 in the tire normal direction from the groove edge of the first circumferential groove to the outer surface of the band layer in the tire radial direction is 15.0 mm or less. Pneumatic tires. [Disclosure 2] The pneumatic tire according to Disclosure 1, wherein the first and second filaments are made of organic fibers. [Disclosure 3] The pneumatic tire according to disclosure 1 or 2, wherein the total fineness of the band cord is 4400 dtex or less. [Disclosure 4] The pneumatic tire according to any one of disclosures 1 to 3, wherein the stress σ1 of the band cord when stretched by 3% is 0.03 (N / tex) or less. [Disclosure 5] The pneumatic tire according to Disclosure 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). [Disclosure 6] The pneumatic tire according to any one of disclosures 1 to 5, wherein the stress σ2 of the band cord when stretched by 5% is 0.04 to 0.06 (N / tex). [Disclosure 7] The pneumatic tire according to disclosure 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). [Disclosure 8] The pneumatic tire according to any one of disclosures 1 to 7, wherein the see-through ratio of the contact surface of the tread portion is 15% to 50%. [Disclosure 9] The pneumatic tire according to Disclosure 8, wherein the ratio t1 / d1 (%) of the thickness t1 to the distance d1 is smaller than the shear ratio (%). [Disclosure 10] The tread rubber comprises a rubber composition having a complex modulus of elasticity E*1 of 10 (MPa) or less at 30°C, as described in any of disclosures 1 to 9. [Disclosure 11] The pneumatic tire according to disclosure 10, wherein the product d1·E*1 of the distance d1 (mm) and the complex modulus of elasticity E*1 (MPa) is 5.0 to 30.0 (MPa·mm). [Disclosure 12] The pneumatic tire according to disclosure 10 or 11, wherein the product σ2·E*1 of the stress σ2 (N / tex) of the band cord when it is elongated by 5% and the complex modulus of elasticity E*1 (MPa) is 0.40 to 1.60 (N·MPa / tex). [Disclosure 13] The pneumatic tire according to any one of disclosures 10 to 12, wherein the product of the complex modulus of elasticity E*1 (MPa) and the shear ratio (%) of the contact surface of the tread portion is 5.0 (MPa) or less. [Disclosure 14] The pneumatic tire according to any one of disclosures 1 to 13, wherein the ratio σ1 / σ2 (%) of the stress σ1 (N / tex) of the band cord when it is stretched 3% to the stress σ2 (N / tex) of the band cord when it is stretched 5% is greater than the see-through ratio (%) of the contact surface of the tread portion. [Disclosure 15] The aforementioned thickness t1 is 0.05 to 0.30 mm. The aforementioned distance d1 is 0.5 to 1.5 mm. The pneumatic tire according to any one of disclosures 1 to 14, wherein the distance d2 is 5.0 to 12.0 mm.

Claims

1. A pneumatic tire having a tread section, The tread portion includes a tread rubber that constitutes the contact surface and a band layer arranged on the radially inward side of the tread rubber. The tread rubber is provided with a first circumferential groove that extends continuously in the tire circumferential direction along the contact surface. The band layer includes band cords arranged substantially parallel to the circumferential direction of the tire, and a topping rubber covering the band cords. The aforementioned band cord is a hybrid cord formed by twisting together a first filament and a second filament having a lower modulus of elasticity than the first filament. In the region of the first circumferential groove on the radially inner side of the tire, the maximum thickness t1 of the topping rubber on the radially outer side of the band cord is 1.0 mm or less. The minimum distance d1 from the bottom of the first circumferential groove to the outer surface of the band layer in the tire radial direction is 2.0 mm or less. The distance d2 in the tire normal direction from the groove edge of the first circumferential groove to the outer surface of the band layer in the tire radial direction is 15.0 mm or less. The product σ²·E*1 of the stress σ² (N / tex) of the band cord when stretched by 5% and the complex modulus E*1 (MPa) of the tread rubber at 30°C is 0.40 to 1.60 (N·MPa / tex). Pneumatic tires.

2. A pneumatic tire having a tread portion, The tread portion includes a tread rubber that constitutes the contact surface and a band layer arranged on the radially inward side of the tread rubber. The tread rubber is provided with a first circumferential groove that extends continuously in the tire circumferential direction along the contact surface. The band layer includes band cords arranged substantially parallel to the circumferential direction of the tire, and a topping rubber covering the band cords. The aforementioned band cord is a hybrid cord formed by twisting together a first filament and a second filament having a lower modulus of elasticity than the first filament. In the region of the first circumferential groove on the radially inner side of the tire, the maximum thickness t1 of the topping rubber on the radially outer side of the band cord is 1.0 mm or less. The minimum distance d1 from the bottom of the first circumferential groove to the outer surface of the band layer in the tire radial direction is 2.0 mm or less. The distance d2 in the tire normal direction from the groove edge of the first circumferential groove to the outer surface of the band layer in the tire radial direction is 15.0 mm or less. The stress σ1 of the aforementioned band cord when elongated by 3% is 0.03 (N / tex) or less. Pneumatic tires.

3. A pneumatic tire having a tread portion, The tread portion includes a tread rubber that constitutes the contact surface and a band layer arranged on the radially inward side of the tread rubber. The tread rubber is provided with a first circumferential groove that extends continuously in the tire circumferential direction along the contact surface. The band layer includes band cords arranged substantially parallel to the circumferential direction of the tire, and a topping rubber covering the band cords. The aforementioned band cord is a hybrid cord formed by twisting together a first filament and a second filament having a lower modulus of elasticity than the first filament. In the region of the first circumferential groove on the radially inner side of the tire, the maximum thickness t1 of the topping rubber on the radially outer side of the band cord is 1.0 mm or less. The minimum distance d1 from the bottom of the first circumferential groove to the outer surface of the band layer in the tire radial direction is 2.0 mm or less. The distance d2 in the tire normal direction from the groove edge of the first circumferential groove to the outer surface of the band layer in the tire radial direction is 15.0 mm or less. The product σ1・d2 between the stress σ1 (N / tex) of the band cord when it is elongated by 3% and the distance d2 (mm) is 0.05 to 0.40 (N・mm / tex). Pneumatic tires.

4. A pneumatic tire having a tread portion, The tread portion includes a tread rubber that constitutes the contact surface and a band layer arranged on the radially inward side of the tread rubber. The tread rubber is provided with a first circumferential groove that extends continuously in the tire circumferential direction along the contact surface. The band layer includes band cords arranged substantially parallel to the circumferential direction of the tire, and a topping rubber covering the band cords. The aforementioned band cord is a hybrid cord formed by twisting together a first filament and a second filament having a lower modulus of elasticity than the first filament. In the region of the first circumferential groove on the radially inner side of the tire, the maximum thickness t1 of the topping rubber on the radially outer side of the band cord is 1.0 mm or less. The minimum distance d1 from the bottom of the first circumferential groove to the outer surface of the band layer in the tire radial direction is 2.0 mm or less. The distance d2 in the tire normal direction from the groove edge of the first circumferential groove to the outer surface of the band layer in the tire radial direction is 15.0 mm or less. The stress σ² of the aforementioned band cord when elongated by 5% is 0.04 to 0.06 (N / tex). Pneumatic tires.

5. A pneumatic tire having a tread portion, The tread portion includes a tread rubber that constitutes the contact surface and a band layer arranged on the radially inward side of the tread rubber. The tread rubber is provided with a first circumferential groove that extends continuously in the tire circumferential direction along the contact surface. The band layer includes band cords arranged substantially parallel to the circumferential direction of the tire, and a topping rubber covering the band cords. The aforementioned band cord is a hybrid cord formed by twisting together a first filament and a second filament having a lower modulus of elasticity than the first filament. In the region of the first circumferential groove on the radially inner side of the tire, the maximum thickness t1 of the topping rubber on the radially outer side of the band cord is 1.0 mm or less. The minimum distance d1 from the bottom of the first circumferential groove to the outer surface of the band layer in the tire radial direction is 2.0 mm or less. The distance d2 in the tire normal direction from the groove edge of the first circumferential groove to the outer surface of the band layer in the tire radial direction is 15.0 mm or less. The product σ2・d2 between the stress σ2 (N / tex) of the band cord when it is elongated by 5% and the distance d2 (mm) is 0.30 to 0.60 (N・mm / tex). Pneumatic tires.

6. A pneumatic tire having a tread portion, The tread portion includes a tread rubber that constitutes the contact surface and a band layer arranged on the radially inward side of the tread rubber. The tread rubber is provided with a first circumferential groove that extends continuously in the tire circumferential direction along the contact surface. The band layer includes band cords arranged substantially parallel to the circumferential direction of the tire, and a topping rubber covering the band cords. The aforementioned band cord is a hybrid cord formed by twisting together a first filament and a second filament having a lower modulus of elasticity than the first filament. In the region of the first circumferential groove on the radially inner side of the tire, the maximum thickness t1 of the topping rubber on the radially outer side of the band cord is 1.0 mm or less. The minimum distance d1 from the bottom of the first circumferential groove to the outer surface of the band layer in the tire radial direction is 2.0 mm or less. The distance d2 in the tire normal direction from the groove edge of the first circumferential groove to the outer surface of the band layer in the tire radial direction is 15.0 mm or less. The product of the complex modulus E*1 (MPa) of the tread rubber at 30°C and the shear ratio (%) of the contact surface of the tread portion is 5.0 (MPa) or less. Pneumatic tires.

7. A pneumatic tire having a tread portion, The tread portion includes a tread rubber that constitutes the contact surface and a band layer arranged on the radially inward side of the tread rubber. The tread rubber is provided with a first circumferential groove that extends continuously in the tire circumferential direction along the contact surface. The band layer includes band cords arranged substantially parallel to the circumferential direction of the tire, and a topping rubber covering the band cords. The aforementioned band cord is a hybrid cord formed by twisting together a first filament and a second filament having a lower modulus of elasticity than the first filament. In the region of the first circumferential groove on the radially inner side of the tire, the maximum thickness t1 of the topping rubber on the radially outer side of the band cord is 1.0 mm or less. The minimum distance d1 from the bottom of the first circumferential groove to the outer surface of the band layer in the tire radial direction is 2.0 mm or less. The distance d2 in the tire normal direction from the groove edge of the first circumferential groove to the outer surface of the band layer in the tire radial direction is 15.0 mm or less. The ratio σ1 / σ2 (%) of the stress σ1 (N / tex) of the band cord when it is stretched 3% to the stress σ2 (N / tex) of the band cord when it is stretched 5% is greater than the see-through ratio (%) of the contact surface of the tread portion. Pneumatic tires.

8. The pneumatic tire according to any one of claims 1 to 7, wherein the first filament and the second filament are made of organic fibers.

9. The pneumatic tire according to any one of claims 1 to 8, wherein the total fineness of the band cord is 4400 dtex or less.

10. The pneumatic tire according to any one of claims 1 to 9, wherein the see-through ratio of the contact surface of the tread portion is 15% to 50%.

11. The pneumatic tire according to any one of claims 1 to 10, wherein the ratio t1 / d1 (%) of the thickness t1 to the distance d1 is smaller than the see ratio (%) of the contact surface of the tread portion.

12. The pneumatic tire according to any one of claims 1 to 11, wherein the tread rubber comprises a rubber composition having a complex modulus of elasticity E*1 of 10 (MPa) or less at 30°C.

13. The pneumatic tire according to any one of claims 1 to 12, wherein the distance d1 is 1.0 to 1.5 mm.

14. The pneumatic tire according to any one of claims 1 to 13, wherein the product d1・E*1 of the distance d1 (mm) and the complex modulus of elasticity E*1 (MPa) of the tread rubber at 30°C is 5.0 to 30.0 (MPa・mm).

15. The aforementioned thickness t1 is 0.05 to 0.30 mm. The pneumatic tire according to any one of claims 1 to 14, wherein the distance d2 is 5.0 to 12.0 mm.

Images