JP2009214769A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire that achieves an improvement in high-speed durability and ride comfort while excellently maintaining a steering stability during high-speed traveling under the condition that a large negative camber is set. <P>SOLUTION: The pneumatic tire is configured as follows. A carcass layer 4, having one ply structure, with a cord angle in the range of 75-90° with respect to the tire circumferential direction is mounted across a pair of bead parts. A belt layer 8 is arranged on the outer peripheral side of the carcass layer 4. The carcass layer 4 is wound up from the tire inside to the tire outside around a bead core 5. A bead filler 6 is sandwiched by the body part 4a and the winding-up part 4b of the carcass layer 4 while the winding-up part 4b of the carcass layer 4 is extended to the lower region of the belt layer 8 so as to overlap the end of the belt layer 8. An asymmetrical structure is formed such that a side reinforcing layer 7 is buried only in the bead part 3 on the vehicle outside when mounted to a vehicle. A height RH of the side reinforcing layer 7 from a bead heel is set to 30-65% of a cross-sectional height SH of a tire so as to be higher than a height FH of the bead filler 6. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic tire having a carcass layer having a one-ply structure and a winding portion extending to a lower region of the belt layer so as to overlap an end portion of the belt layer, and more specifically, a large negative camber is set. It is related with the pneumatic tire which made it possible to improve high-speed durability and a ride comfort, maintaining favorable steering stability at the time of high-speed driving | running | working on conditions.

  In recent years, the demand for weight reduction of pneumatic tires mounted on vehicles that are expected to run at high speed, such as sports cars, has become stricter. It is required to ensure the handling stability.

  On the other hand, a carcass layer having a one-ply structure is mounted between a pair of bead portions, a belt layer is disposed on the outer peripheral side of the carcass layer in the tread portion, and the carcass layer is disposed around each bead core disposed on each bead portion. The bead filler disposed on the bead core is sandwiched between the body portion and the winding portion of the carcass layer, and the lower portion of the belt layer is overlapped with the end portion of the belt layer. A pneumatic tire extended to the region has been proposed (see, for example, Patent Documents 1 to 3).

  A pneumatic tire having a carcass layer that extends to the lower region of the belt layer so as to overlap the end portion of the belt layer with a one-ply structure as described above is lightweight by using the carcass layer as one ply. In the sidewall portion, excellent steering stability can be exhibited by overlapping the main body portion and the winding portion of the carcass layer. Further, when a side reinforcing layer is embedded in the pair of left and right bead portions, it is possible to ensure a higher level of steering stability.

  However, a large negative camber is usually set for a vehicle that is assumed to run at high speed, and when a side reinforcing layer is embedded in the bead portion of a pneumatic tire mounted on such a vehicle, the tire flex zone is sufficient. Therefore, there is a problem that the high-speed durability is lowered and the ride comfort is deteriorated.

In addition, a pneumatic tire having a carcass layer that extends to a lower region of the belt layer so that the winding portion overlaps with an end portion of the belt layer in a one-ply structure, for example, when continuous running in circuit running is performed, The steering stability tends to decrease with the generation of heat. Therefore, it is also required to suppress a change in performance of steering stability due to continuous running for a pneumatic tire that achieves both weight reduction and steering stability based on the above structure.
JP-A-5-238208 JP-A-6-16609 JP 2000-52709 A

  An object of the present invention is to provide a pneumatic tire capable of improving high-speed durability and ride comfort while maintaining good steering stability during high-speed driving under conditions where a large negative camber is set. There is to do.

  In order to achieve the above object, the pneumatic tire of the present invention is a pneumatic tire in which the mounting direction of the front and back of the tire is specified when the vehicle is mounted, and the cord angle between the pair of bead portions with respect to the tire circumferential direction is 75 °. A carcass layer having a one-ply structure in a range of ˜90 ° is mounted, a belt layer is arranged on the outer peripheral side of the carcass layer in the tread portion, and the carcass layer is arranged around the bead core arranged in each bead portion inside the tire. The bead filler disposed on the bead core is sandwiched between the body portion and the winding portion of the carcass layer, and the winding portion of the carcass layer is overlapped with the end portion of the belt layer. A pneumatic tire that extends to the lower area has an asymmetric structure with a side reinforcement layer embedded only in the bead outside the vehicle when the vehicle is installed. And the height of the side reinforcing layer from the bead heel is 30% to 65% of the tire cross-sectional height, which is higher than the height of the bead filler.

  In the present invention, in order to achieve both weight reduction and steering stability, an air having a carcass layer having a one-ply structure in which a winding portion extends to a lower region of the belt layer so as to overlap an end portion of the belt layer. A tire on the outer side of the vehicle is formed by forming an asymmetric structure in which a side reinforcing layer is embedded only in the bead portion on the outer side of the vehicle when the vehicle is mounted and defining the height of the side reinforcing layer from the bead heel. The flex zone inside the vehicle is widened while ensuring rigidity, so even under conditions where a large negative camber is set, high-speed durability and ride comfort are improved while maintaining good steering stability during high-speed driving. be able to.

In the present invention, the height of the bead filler from the bead heel is 25 mm or less, the cross-sectional area of the bead filler is 65 mm ² or less, and the tan δ at 60 ° C. of the rubber composition constituting the bead filler is 0.20 or less. It is preferable to do. In this way, the bead filler that is repeatedly deformed during rolling of the tire is lowered, the cross-sectional area thereof is reduced, and the tan δ at 60 ° C. of the rubber composition constituting the bead filler is lowered, thereby continuously running on the circuit. It is possible to suppress the heat generation of the tire due to, and to suppress the performance change of the steering stability. Thereby, it is possible to maintain the initial steering stability for a long time in continuous running.

  In the tread portion, at least two kinds of cap tread rubber layers having different rubber compositions are arranged adjacent to each other in the tire width direction, and tan δ at 60 ° C. of the rubber composition constituting the cap tread rubber layer on the vehicle outer side is determined. It is preferable to make it higher than tan δ at 60 ° C. of the rubber composition constituting the cap tread rubber layer on the inside of the vehicle. Generally, when the tan δ at 60 ° C. of the rubber composition constituting the cap tread rubber layer is increased, the steering stability is improved, but the performance of the steering stability due to heat generation is likely to occur. On the other hand, as described above, tan δ is relatively high on the outside of the vehicle and tan δ is relatively low on the inside of the vehicle, thereby improving the steering stability and changing the performance of the steering stability by continuous running. Can be suppressed.

  The ratio of the maximum value tan δH and the minimum value tan δL (tan δH / tan δL) of tan δ at 60 ° C of the rubber composition constituting at least two kinds of cap tread rubber layers is preferably in the range of 1.05 to 1.80. . Thereby, the effect which suppresses the performance change of the steering stability by continuous driving | running | working can fully be acquired, improving steering stability.

  It is preferable that the boundary between at least two types of cap tread rubber layers is disposed below the main groove extending in the tire circumferential direction at the tread portion. Thereby, generation | occurrence | production of the partial wear by the difference in a rubber composition can be suppressed.

  Further, at least one main groove extending in the tire circumferential direction is provided in the tread portion, and the groove area ratio GAo from the tread center to the ground contact area outside the vehicle is the groove area ratio GAi from the tread center to the ground contact area inside the vehicle. It is preferable to form an asymmetric tread pattern that is smaller than that. Thereby, the effect which suppresses the performance change of the steering stability by continuous driving | running | working can fully be acquired, improving steering stability.

  In the asymmetric tread pattern, the groove area ratio GA in the entire ground contact area is in the range of 20% to 40%, and the groove area ratio GAo in the ground contact area outside the vehicle and the groove area ratio GAi in the ground contact area inside the vehicle are The difference (GAi−GAo) is preferably in the range of 1% to 15%. Thereby, the effect which suppresses the performance change of the steering stability by continuous driving | running | working can fully be acquired, improving steering stability.

  In the present invention, the height of the bead filler from the bead heel is a height measured under the tire dimension measurement conditions defined in the standard on which the tire is based, and the height of the bead filler from the bead heel corresponding to the reference position of the rim diameter. This is the dimension in the tire radial direction up to the top. Similarly, the height of the side reinforcement layer from the bead heel is a height measured under the tire dimension measurement conditions defined in the standard on which the tire is based, and is from the bead heel to the side reinforcement layer corresponding to the reference position of the rim diameter. It is the dimension of the tire radial direction to the top of. The tan δ at 60 ° C. is measured using a viscoelastic spectrometer (manufactured by Toyo Seiki Seisakusho) under the conditions of a temperature of 60 ° C., a frequency of 20 Hz, an initial strain of 10%, and a dynamic strain of ± 2%. The groove area ratio is the ratio (%) of the groove area in the ground contact area to the total area of the ground contact area measured under the tire static load radius measurement condition defined by the standard on which the tire is based.

  The present invention can be applied to various types of pneumatic tires. However, when the present invention is applied to a pneumatic tire having a tire size having a flatness ratio of 50% or less with a narrow flex zone, a remarkable effect can be obtained. In particular, when applied to a pneumatic tire mounted on a vehicle having a camber angle of −0.5 ° to −4.0 °, a remarkable effect can be obtained.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows a pneumatic tire according to an embodiment of the present invention. This pneumatic tire is a tire in which the mounting direction of the tire front and back when the vehicle is mounted is designated. In FIG. 1, IN is the inside of the vehicle when the vehicle is mounted, and OUT is the outside of the vehicle when the vehicle is mounted.

  In FIG. 1, 1 is a tread portion, 2 is a sidewall portion, and 3 is a bead portion. As shown in FIG. 1, a single carcass layer 4 composed of a plurality of aligned carcass cords is mounted between a pair of bead portions 3 and 3. As the carcass cord, an organic fiber cord made of rayon, polyester, nylon, aromatic polyamide or the like is preferably used. The cord angle of the carcass layer 4 with respect to the tire circumferential direction is set in the range of 75 ° to 90 °, preferably in the range of 80 ° to 87 °. The cord angle of the carcass layer 4 with respect to the tire circumferential direction is, for example, a high angle when the load factor is low, and a low angle when the load factor is high. The performance can be maintained. The carcass layer 4 is wound up around the bead core 5 from the inside of the tire to the outside. That is, the carcass layer 4 includes a main body portion 4a and a winding portion 4b with the bead core 5 as a boundary.

  In each bead portion 3, a bead filler 6 made of a rubber composition having a high hardness is disposed on the outer periphery of the bead core 5, and the bead filler 6 is sandwiched between the main body portion 4 a and the winding portion 4 b of the carcass layer 4. . Of the pair of left and right bead portions 3, a side reinforcement layer 7 including a reinforcement cord that is inclined with respect to the tire circumferential direction is embedded in the bead portion 3 outside the vehicle, and the side reinforcement layer 7 is embedded in the bead portion 3 inside the vehicle. The equivalent is not buried. In order to obtain a good reinforcing effect, the cord angle of the side reinforcing layer 7 with respect to the tire circumferential direction is desirably set to 15 ° to 65 °. As the reinforcing cord of the side reinforcing layer 7, a steel cord can be used in addition to an organic fiber cord made of polyester, nylon, aromatic polyamide or the like. When an organic fiber cord is used as the reinforcing cord of the side reinforcing layer 7, the side reinforcing layer 7 is preferably arranged so as to wrap the bead core 5 and the bead filler 6 as illustrated. When using a steel cord as the reinforcing cord of the side reinforcing layer 7, the side reinforcing layer 7 may be disposed between the bead filler 6 and the winding portion 4 b of the carcass layer 4.

  On the other hand, a plurality of belt layers 8 including reinforcing cords inclined with respect to the tire circumferential direction are disposed on the outer peripheral side of the carcass layer 4 in the tread portion 1. Further, a belt cover layer 9 including reinforcing cords oriented in the tire circumferential direction is disposed on the outer peripheral side of the belt layer 8. And the winding part 4b of the carcass layer 4 mentioned above is extended to the downward area of this belt layer 8 so that it may overlap with the edge part of the tire width direction of the belt layer 8. FIG.

  In the pneumatic tire described above, in order to achieve both weight reduction and steering stability, a carcass having a one-ply structure in which the winding portion 4b extends to the lower region of the belt layer 8 so as to overlap the end portion of the belt layer 8. Although the layer 4 is provided, an asymmetric structure in which the side reinforcing layer 7 is embedded only in the bead portion 3 outside the vehicle when the vehicle is mounted is formed, and the height RH of the side reinforcing layer 7 from the bead heel is defined as the tire cross-sectional height. 30% to 65% of SH, and the height RH of the side reinforcing layer 7 is set higher than the height FH of the bead filler 6.

  Thus, in the pneumatic tire in which the mounting direction of the front and back of the tire is specified when the vehicle is mounted, an asymmetric structure in which the side reinforcing layer 7 is embedded only in the bead portion 3 outside the vehicle is formed, and the side reinforcing layer 7 is separated from the bead heel. By prescribing the height RH, the flex zone on the inside of the vehicle is widened while ensuring the rigidity of the tire on the outside of the vehicle, so that even when a large negative camber is set, steering stability at high speeds is improved. High speed durability and riding comfort can be improved while maintaining. For example, when a high-speed durability test with a camber is performed, the durability level is suppressed by suppressing the separation between the edge of the belt layer 8 and the carcass layer 4 and between the carcass layer 4 and the side rubber adjacent thereto. Can be increased. In addition, with regard to steering stability during high-speed traveling, particularly high-speed lane change performance can be improved.

  Here, if the height RH of the side reinforcing layer 7 from the bead heel is less than 30% of the tire cross-section height SH, the steering stability at high speed running is insufficient, and conversely if it exceeds 65%, the high speed durability is reduced. Will do. Moreover, the steering stability at the time of high-speed driving | running | working becomes insufficient with the height RH of the side reinforcement layer 7 rather than the height FH of the bead filler 6. FIG.

In the pneumatic tire, the height FH of the bead filler 6 from the bead heel is set to 25 mm or less, the cross-sectional area of the bead filler 6 in the tire meridian section is set to 65 mm ² or less, and the rubber composition constituting the bead filler 6 Tan δ at 60 ° C. is set to 0.20 or less.

  In a pneumatic tire, the deformation of the bead filler 6 is repeated at the time of rolling. When the amount of heat generated due to the bead filler 6 increases thereby, a change in performance of steering stability becomes remarkable. Therefore, by lowering the bead filler 6 and reducing its cross-sectional area, the tan δ at 60 ° C. of the rubber composition constituting the bead filler 6 is reduced to suppress the heat generation of the tire due to continuous running on the circuit. , The performance change of the steering stability can be suppressed. As a result, it is possible to maintain the initial steering stability for a long time in continuous running.

  Here, if the height FH of the bead filler 6 is more than 25 mm, the effect of suppressing the performance change of the steering stability becomes insufficient. The lower limit value of the height FH of the bead filler 6 is preferably 10 mm.

Similarly, if the cross-sectional area of the bead filler 6 exceeds 65 mm ² , the effect of suppressing the change in performance of the steering stability becomes insufficient. The lower limit value of the cross-sectional area of the bead filler 6 is preferably 15 mm ² .

  Further, if the tan δ at 60 ° C. of the rubber composition constituting the bead filler 6 is more than 0.20, the effect of suppressing the performance change of the steering stability becomes insufficient. The lower limit value of tan δ at 60 ° C. of the rubber composition constituting the bead filler 6 is preferably 0.03.

  In the tire in which the tire front and back mounting directions are specified as described above, as shown in FIG. 1, two types of cap tread rubber layers 1A and 1B having different rubber compositions are adjacent to the tread portion 1 in the tire width direction. Is arranged. The tan δ at 60 ° C. of the rubber composition constituting the cap tread rubber layer 1A on the vehicle outer side is higher than the tan δ at 60 ° C. of the rubber composition constituting the cap tread rubber layer 1B on the vehicle inner side. Yes. By providing a difference in the tan δ of the rubber composition of the cap tread rubber layers 1A and 1B, it is possible to suppress the heat generation in the tread portion 1 and to suppress the change in performance of the steering stability while improving the steering stability. become. The range of tan δ at 60 ° C. of the rubber composition constituting the cap tread rubber layer is preferably 0.10 to 0.50.

  The ratio of tan δH at 60 ° C. of the rubber composition constituting the cap tread rubber layer 1A to tan δL at 60 ° C. of the rubber composition constituting the cap tread rubber layer 1B (tan δH / tan δL) is 1.05-1.80. More preferably, it is set in the range of 1.10 to 1.50. If this ratio (tan δH / tan δL) is too small, the effect of suppressing the change in performance of steering stability is reduced, and conversely, if it is too large, the originally required grip force cannot be obtained. The boundary between the cap tread rubber layers 1A and 1B is preferably disposed below the main groove 60 extending in the tire circumferential direction at the tread portion 1. Thereby, generation | occurrence | production of the partial wear by the difference in a rubber composition can be suppressed.

  In this embodiment, two types of cap tread rubber layers 1A and 1B having different rubber compositions are arranged in the tread portion 1, but two or more types of cap tread rubber layers are arranged adjacent to each other in the tire width direction. be able to.

  FIG. 2 shows a tread pattern of a pneumatic tire according to an embodiment of the present invention. In FIG. 2, CL is a tread center. As shown in FIG. 2, a plurality of main grooves 60 extending in the tire circumferential direction are formed in the tread portion 1, and a plurality of land portions 10, 20, 30 are formed by the main grooves 60 from the vehicle outer side toward the vehicle inner side. , 40, 50 are partitioned. The land portion 10 located on the outermost side of the vehicle has a narrow groove 11 extending in the tire circumferential direction, a plurality of lateral grooves 12 extending in the tire width direction on the tread shoulder side from the narrow groove 11, and at least the tread than the narrow groove 11. A plurality of narrow grooves 13 extending in the tire width direction on the center side are formed. The land portion 20 is formed with narrow grooves 21 extending in the tire circumferential direction and a plurality of cutout grooves 22 extending in the tire width direction. The land portion 30 is formed with a plurality of curved grooves 31 extending while being curved in the tire circumferential direction, and a plurality of cutout grooves 32 extending in the tire width direction. The land portion 40 has a tire circumferential direction. A plurality of curved grooves 41 extending while being curved are formed. A plurality of lateral grooves 51 extending in the tire width direction and a plurality of narrow grooves 52 extending in the tire width direction are formed between the lateral grooves 51 in the land portion 50 located on the innermost side of the vehicle.

  In the pneumatic tire described above, at least one main groove 60 extending in the tire circumferential direction is formed in the tread portion 1, and in the entire ground contact region defined by the ground contact width TCW, in the ground contact region outside the vehicle from the tread center CL. Has an asymmetric tread pattern in which the groove area ratio GAo is smaller than the groove area ratio GAi in the ground contact region inside the vehicle from the tread center CL. Thereby, the effect which suppresses the performance change of the steering stability by continuous driving | running | working can fully be acquired, improving steering stability.

  Here, the groove area ratio GA in the entire ground contact area ranges from 20% to 40%, and the groove area ratio GAo in the ground contact area outside the vehicle from the tread center CL and the groove in the ground contact area inside the vehicle from the tread center CL. The difference from the area ratio GAi (GAi−GAo) is preferably in the range of 1% to 15%, more preferably in the range of 2% to 13%. If this difference (GAi−GAo) is too small, the effect of suppressing the change in performance of the steering stability is reduced. On the other hand, if it is too large, the steering stability is lowered due to insufficient block rigidity.

  With a tire size of 235 / 40R18, a carcass layer having a one-ply structure with a cord angle with respect to the tire circumferential direction of 85 ° is mounted between a pair of bead portions, and a belt layer is disposed on the outer peripheral side of the carcass layer in the tread portion, The carcass layer is wound around the bead core disposed on each bead portion from the inside of the tire to the outside, the bead filler disposed on the bead core is sandwiched between the body portion and the wound portion of the carcass layer, and the wound portion of the carcass layer is belted In the pneumatic tire extended to the lower region of the belt layer so as to overlap with the end of the layer, the height of the bead filler from the bead heel, the cross-sectional area of the bead filler, and the rubber composition constituting the bead filler of 60 ° C Tan δ, the material and height of the side reinforcement layer on the vehicle outer side and the vehicle inner side (ratio to the tire cross-section height), vehicle Comparative Examples 1 to 8 and Examples 1 to 6 in which the tan δ at 60 ° C. of the rubber composition constituting the cap tread rubber layers on both the outer side and the inner side of the vehicle, and the groove area ratio on the outer side and the inner side of the vehicle were set as shown in Table 1. 5 tires were produced. In addition, when an aramid fiber cord was used for the side reinforcing layer, the side reinforcing layer was disposed so as to wrap the bead core and the bead filler. Further, when a steel cord is used for the side reinforcing layer, the side reinforcing layer is disposed between the bead filler and the rolled-up portion of the carcass layer.

  With respect to these test tires, performance changes in high speed durability, high speed lane change performance, riding comfort, and steering stability were evaluated by the following test methods, and the results are also shown in Table 1.

High speed durability:
The test tire is mounted on a drum testing machine, the load is 0.85 times the maximum load capacity, the air pressure is 250 kPa, the camber angle is -2.5 °, and the speed is from 200 km / h to 10 km / h every 10 minutes. We stepped up step by step and measured the distance traveled until the tire broke down. The evaluation results are shown as an index with Comparative Example 1 as 100. It means that high speed durability is excellent, so that this index value is large.

High-speed lane change performance:
The test tire is fitted to a wheel with a rim size of 18 x 8 J and mounted on a vehicle with a displacement of 4000 cc class (camber angle: -2.5 °). A running test is conducted by a test driver under the condition of an air pressure of 250 kPa. Sensory evaluation was performed on the lane change. The evaluation results are shown as an index with Comparative Example 1 as 100. The larger the index value, the better the high-speed lane change performance.

Ride comfort:
The test tire is fitted to a wheel with a rim size of 18 x 8 J and mounted on a vehicle with a displacement of 4000 cc class (camber angle: -2.5 °), and a running test is conducted by a test driver under the condition of an air pressure of 250 kPa. A sensory evaluation was performed on the comfort. The evaluation results are shown as an index with Comparative Example 1 as 100. The larger the index value, the better the ride comfort.

Steering stability performance change:
The test tire is fitted to a wheel with a rim size of 18 x 8 J and mounted on a vehicle with a displacement of 4000 cc (camber angle: -2.5 °). The test driver runs continuously for 200 km under the condition of air pressure of 250 kPa. The sensory evaluation was performed on the change between the driving stability at the beginning of driving and the driving stability at the end of driving. The evaluation results are indicated by an index with a pass level of 100. A larger index value means less performance change.

  As shown in Table 1, the tires of Examples 1 to 5 are in good contrast with Comparative Example 1 while maintaining good steering stability during high-speed driving under the condition that a large negative camber is set. It exhibited excellent high-speed durability and ride comfort, and there was little change in performance of steering stability due to continuous running. On the other hand, Comparative Examples 2 to 8 could not obtain a sufficient improvement effect on the handling stability, the high speed durability and the riding comfort during high speed running.

It is meridian sectional drawing which shows the pneumatic tire which consists of embodiment of this invention. It is a top view which shows the tread pattern of the pneumatic tire which consists of embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tread part 1A, 1B Cap tread rubber layer 2 Side wall part 3 Bead part 4 Carcass layer 4a Main body part 4b Roll-up part 5 Bead core 6 Bead filler 7 Side reinforcement layer 8 Belt layer 9 Belt cover layer 60 Main groove

Claims (9)

  A pneumatic tire in which a tire front and back mounting direction is specified when the vehicle is mounted, and a carcass layer having a one-ply structure in which a cord angle with respect to the tire circumferential direction is in a range of 75 ° to 90 ° between a pair of bead portions. The belt layer is arranged on the outer peripheral side of the carcass layer in the tread portion, the carcass layer is wound up around the bead core arranged in each bead portion from the inside of the tire to the outside, and the bead filler arranged on the bead core is provided. In a pneumatic tire that is sandwiched between a main body portion and a winding portion of the carcass layer, and that the winding portion of the carcass layer extends to a lower region of the belt layer so as to overlap an end portion of the belt layer, when mounted on a vehicle An asymmetric structure in which a side reinforcing layer is embedded only in the bead portion outside the vehicle is formed, and the height of the side reinforcing layer from the bead heel is tied. A pneumatic tire having a height higher than that of the bead filler as 30% to 65% of the height of the cross section. The height from the bead heel of the bead filler is 25 mm or less, the cross-sectional area of the bead filler is 65 mm ² or less, and the tan δ at 60 ° C. of the rubber composition constituting the bead filler is 0.20 or less. The pneumatic tire according to 1.   At least two kinds of cap tread rubber layers having different rubber compositions are arranged in the tread portion so as to be adjacent to each other in the tire width direction, and tan δ at 60 ° C. of the rubber composition constituting the cap tread rubber layer on the vehicle outer side is determined. The pneumatic tire according to claim 1 or claim 2, wherein the rubber composition constituting the cap tread rubber layer on the inner side of the vehicle is higher than tan δ at 60 ° C.   The ratio (tan δH / tan δL) of the maximum value tan δH and the minimum value tan δH of tan δ at 60 ° C of the rubber composition constituting the at least two kinds of cap tread rubber layers is in the range of 1.05-1.80. 3. The pneumatic tire according to 3.   5. The pneumatic tire according to claim 3, wherein a boundary between the at least two types of cap tread rubber layers is disposed under a main groove extending in a tire circumferential direction at a tread portion.   The tread portion is provided with at least one main groove extending in the tire circumferential direction, and the groove area ratio GAo from the tread center to the vehicle outer contact area is greater than the groove area ratio GAi from the tread center to the vehicle inner contact area. The pneumatic tire according to any one of claims 1 to 5, wherein an asymmetric tread pattern is also formed.   The difference between the groove area ratio GAo in the ground contact area outside the vehicle and the groove area ratio GAi in the ground contact area inside the vehicle (GAi−GAo) where the groove area ratio GA in the entire ground contact area is 20% to 40%. The pneumatic tire according to claim 6, wherein the range is from 1% to 15%.   The pneumatic tire according to any one of claims 1 to 7, having a tire size with a flatness ratio of 50% or less.   The pneumatic tire according to any one of claims 1 to 8, which is mounted on a vehicle having a camber angle of -0.5 ° to -4.0 °.

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