JP2019073248A - Pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire capable of improving noise performance while excellently maintaining uneven wear resistance.SOLUTION: A tread part 1 comprises at least three main grooves 10 extending in a tire circumferential direction, and the main grooves 10 include two shoulder main grooves 12 positioned at the outermost side in a tire width direction and at least one center main groove 11 positioned between the shoulder main grooves 12. A plurality of rib rows 10 are partitioned by the main grooves 10 and grounding ends E on opposite sides in the tire width direction. When a rubber thickness at a central position in the width direction of the respective rib rows 10 is defined as a reference thickness Ho of the rib rows, a rubber thickness Hce of the respective rib rows 10 at both edge positions of the center main groove 11 is larger than the references thickness Ho corresponding to it, and a rubber thickness Hsh of the respective rib rows 10 at both edge positions of the shoulder main grooves 12 is smaller than the reference thickness Ho corresponding to it.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pneumatic tire provided with a plurality of main grooves extending in the circumferential direction of the tire in a tread portion, and more specifically, it is possible to improve noise performance while maintaining good resistance to uneven wear. It relates to a pneumatic tire.

  The pneumatic tire generally includes a plurality of main grooves extending in the circumferential direction of the tire in the tread portion, and a plurality of rib rows are divided by the main grooves. When such a pneumatic tire travels on a smooth road surface, air column resonance noise is generated due to the main groove. On the other hand, in recent years, as the quietness of the vehicle is improved, air column resonance noise caused by the main groove of the pneumatic tire tends to become apparent. Therefore, reduction of air column resonance sound is strongly required (for example, refer to patent documents 1-3).

  The frequency of air column resonance is determined by the contact length of the main groove included in the contact surface of the pneumatic tire. Therefore, the ground contact shape of the pneumatic tire is rounded, and a difference is made between the ground contact length of the main groove disposed in the center region of the tread portion and the ground contact length of the main groove disposed in the shoulder region of the tread portion. It is conceivable to disperse the frequency of air column resonance noise caused by the main groove. However, when the ground contact shape of the pneumatic tire is rounded, there is a concern that the uneven wear resistance may be deteriorated. Therefore, it is not the best solution to reduce air column resonance based on the setting of the ground contact shape.

JP, 2016-40156, A JP, 2016-145009, A JP, 2016-199118, A

  An object of the present invention is to provide a pneumatic tire capable of improving noise performance while maintaining good resistance to uneven wear.

A pneumatic tire according to the present invention for achieving the above object comprises a tread portion extending in the circumferential direction of the tire to form an annular shape, a pair of sidewall portions disposed on both sides of the tread portion, and these sidewall portions A pneumatic tire including a pair of bead portions disposed inward in the tire radial direction of
The tread portion has at least three main grooves extending in the tire circumferential direction, and the main grooves are at least positioned between the two shoulder main grooves located on the outermost side in the tire width direction and the shoulder main grooves. Including one center main groove,
A plurality of rib rows are divided by the main groove and the ground contact ends on both sides in the tire width direction, and the center main groove is a center main groove when the rubber thickness at the widthwise center position of each rib row is a reference thickness Ho of the rib rows. The rubber thickness Hce of each rib row at both edge positions of is larger than the corresponding reference thickness Ho, and the rubber thickness Hsh of each rib row at both edge positions of the shoulder main groove is the corresponding reference thickness It is characterized by being smaller than H o.

  In the present invention, by making the rubber thickness Hce of each rib row at both edge positions of the center main groove larger than the corresponding reference thickness Ho, grounding of each rib row at both edge positions of the center main groove is made By making the length relatively long and making the rubber thickness Hsh of each rib row at both edge positions of the shoulder main groove smaller than the corresponding reference thickness Ho, each at both edge positions of the shoulder main groove Make the contact length of the rib row relatively short. As a result, the difference between the contact length of the center main groove and the contact length of the shoulder main groove can be increased, and the frequency of air column resonance sound caused by the main groove can be dispersed. It can be reduced. Further, in the above-described method, since it is not necessary to round the contact shape of the pneumatic tire, it is possible to maintain good non-uniform wear resistance.

  In the present invention, the main groove is a groove having a groove width of 3.5 mm to 12 mm, a groove depth of 5 mm to 12 mm, and a wear indicator. A groove shallower than the main groove or a groove narrower than the main groove has a small groove volume, and therefore is not a target of air column resonance noise reduction. The rubber thickness is the thickness from the tread surface to a reinforcing material to be a tire skeleton such as a belt layer or a belt reinforcing layer embedded in the tread portion, and is measured along the normal direction of the reinforcing material .

  In the present invention, there are four main grooves, and the main grooves include two shoulder main grooves located on the outermost side in the tire width direction and two center main grooves located between the shoulder main grooves. It is preferable to include. Thus, in a pneumatic tire having four main grooves in the tread portion, the rubber thickness Hce of each rib row at both edge positions of the center main groove and each rib row at both edge positions of the shoulder main groove By appropriately setting the rubber thickness Hsh, it is possible to achieve both uneven wear resistance and noise performance without adversely affecting drainage performance and steering stability.

The difference ΔHce between the rubber thickness Hce of each rib row and the corresponding reference thickness Ho at both edge positions of the center main groove is in the range of 0.05 mm to 1.0 mm, and both edge positions of the shoulder main groove are The difference ΔHsh between the rubber thickness Hsh of each rib row and the corresponding reference thickness Ho at 0.0 is 0.0
It is preferably in the range of 5 mm to 1.0 mm. As a result, noise performance can be effectively improved while maintaining good partial wear resistance.

In a pneumatic tire whose mounting direction to a vehicle is specified, when the distance from the tire equator to the center main groove inside the vehicle and the distance from the tire equator to the center main groove outside the vehicle are different from each other, both edges of the center main groove It is preferable that the difference ΔHce between the rubber thickness Hce of each rib row at the position and the corresponding reference thickness Ho be larger as the center main groove is closer to the tire equator. As a result, the contact length of the center main groove near the tire equator is made relatively long, and a difference is made between the contact length of the center main groove inside the vehicle and the contact length of the center main groove outside the vehicle, The effect of dispersing the frequency of air column resonance can be enhanced.

Furthermore, in the pneumatic tire in which the mounting direction to the vehicle is specified, when the distance from the tire equator to the shoulder main groove inside the vehicle and the distance from the tire equator to the shoulder main groove outside the vehicle are different from each other, The difference ΔHsh between the rubber thickness Hsh of each rib row and the corresponding reference thickness Ho at both edge positions is preferably smaller as the shoulder main groove is closer to the tire equator. Thereby, the contact length of the shoulder main groove far from the tire equator is relatively shortened, and a difference is made between the contact length of the shoulder main groove inside the vehicle and the contact length of the shoulder main groove outside the vehicle, The effect of dispersing the frequency of air column resonance can be enhanced.

  In the present invention, the plurality of rib rows are partitioned by the main groove and the ground contact ends on both sides in the tire width direction. The ground contact end is the end in the tire width direction of the ground contact region of the tread portion. The contact area of the tread portion is specified based on the contact width in the tire axial direction measured when a tire is rimmed on a regular rim and filled with a regular internal pressure and placed vertically on a plane and a regular load is applied. Be done. The “regular rim” is a rim that defines the standard for each tire in the standard system including the standard on which the tire is based, for example, the standard rim for JATMA, “Design Rim” for the TRA, or ETRTO In the case of “Measuring Rim”. The “normal internal pressure” is the air pressure specified by each standard in the standard system including the standard to which the tire is based, and in the case of JATMA, the maximum air pressure, in the case of TRA, the table “TIRE ROAD LIMITS AT VARIOUS The maximum value described in "COLD INFlation PRESSURES" is "INFLATION PRESSURE" in the case of ETRTO, but is 180 kPa when the tire is for a passenger car. The “regular load” is a load defined by each standard in the standard system including the standard to which the tire is based, and in the case of JATMA, the maximum load capacity, in the case of TRA, the table “TIRE ROAD LIMITS AT VARIOUS In the case of ETRTO, the maximum value described in "COLD INFlation PRESSURES" is "LOAD CAPACITY", but when the tire is for a passenger car, the load corresponds to 88% of the load.

1 is a meridional cross-sectional view showing a pneumatic tire according to an embodiment of the present invention. It is sectional drawing which expands and shows the principal part of the pneumatic tire of FIG. It is a top view which shows roughly the footprint formed when the tread part of the pneumatic tire of FIG. 1 is earth | grounded. It is sectional drawing which shows the principal part of the pneumatic tire which consists of other embodiment of this invention.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the attached drawings. 1 and 2 show a pneumatic tire according to an embodiment of the present invention.

  As shown in FIG. 1, the pneumatic tire according to the present embodiment includes a tread portion 1 extending in the circumferential direction of the tire to form an annular shape, and a pair of sidewall portions 2 and 2 disposed on both sides of the tread portion 1. And a pair of bead portions 3 and 3 disposed on the inner side in the tire radial direction of the side wall portions 2.

  A carcass layer 4 is mounted between the pair of bead portions 3 and 3. The carcass layer 4 includes a plurality of carcass cords extending in the tire radial direction, and is folded from the inside to the outside around the bead cores 5 disposed in each bead portion 3. A bead filler 6 made of a rubber composition having a triangular cross section is disposed on the outer periphery of the bead core 5.

  On the other hand, a plurality of belt layers 7 are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. The belt layers 7 include a plurality of belt cords inclined with respect to the tire circumferential direction, and the belt cords are arranged so as to cross each other between layers. As a belt cord which constitutes belt layer 7, a steel cord is used preferably. On the outer peripheral side of the belt layer 7, at least one belt reinforcing layer 8 in which band cords are arranged at an angle of, for example, 5 ° or less with respect to the tire circumferential direction is disposed. Preferably, the belt reinforcing layer 8 has a jointless structure in which a strip material formed by aligning at least one band cord and being rubber-coated is continuously wound in the tire circumferential direction. As a band cord which constitutes belt reinforcement layer 8, organic fiber cords, such as nylon and aramid, are preferably used.

  The tread portion 1 is formed with four main grooves 10 extending in the tire circumferential direction. Main groove 10 includes two shoulder main grooves 12 and 12 located on the outermost side in the tire width direction, and two center main grooves 11 and 11 located between shoulder main grooves 12 and 12. It is. A plurality of rib rows 20 are divided by the ground contact end E and the main groove 10 on both sides in the tire width direction of the tread portion 1. That is, the center rib row 21 is defined between the center main grooves 11 and 11, the middle rib row 22 is defined between the center main groove 11 and the shoulder main groove 12, the shoulder main groove 12 and the ground end E And a shoulder rib row 23 is defined therebetween. In each of the center rib row 21, the middle rib row 22 and the shoulder rib row 23, lug grooves and sipes extending in the tire width direction are formed as necessary.

  As shown in FIG. 2, when the rubber thickness at the widthwise center position of each rib row 20 (21, 22, 23) is the reference thickness Ho of the rib row 20, both edge positions of the center main groove 11 The rubber thickness Hce of each rib row 20 is larger than the corresponding reference thickness Ho, and the rubber thickness Hsh of each rib row 20 at both edge positions of the shoulder main groove 12 is the corresponding reference It is smaller than the thickness Ho. That is, in the center rib row 21, the rubber thickness Hce at the position facing the center main groove 11 is larger than the reference thickness Ho of the center rib row 21. In middle rib row 22, rubber thickness Hce at a position facing center main groove 11 is larger than reference thickness Ho of middle rib row 22, and rubber thickness Hsh at a position facing shoulder main groove 12. Is smaller than the reference thickness Ho of the middle rib row 22. In the shoulder rib row 23, the rubber thickness Hsh at the position facing the shoulder main groove 12 is smaller than the reference thickness Ho of the shoulder rib row 23.

  In order to satisfy the relationship between the reference thickness Ho and the rubber thickness Hce, the center rib row 21 and the middle rib row 22 are such that the rubber thickness gradually increases from the widthwise center position toward the center main groove 11 It has a structure. Further, in order to satisfy the relationship between the reference thickness Ho and the rubber thickness Hsh, the middle rib row 22 and the shoulder rib row 23 gradually reduce the rubber thickness from the center position in the width direction toward the shoulder main groove 12 It has a similar structure. More preferably, in the tire meridional section, the contours of the treads of the center rib row 21, the middle rib row 22 and the shoulder rib row 23 are formed by curves having no steps.

  In the pneumatic tire described above, the rubber thickness Hce of each of the rib rows 20 (21, 22) at both edge positions of the center main groove 11 is larger than the corresponding reference thickness Ho. The ribs 20 project outward in the tire radial direction at both edge positions of the tire. Also, the rubber thickness Hsh of each rib row 20 (22, 23) at both edge positions of the shoulder main groove 12 is smaller than the corresponding reference thickness Ho, and at both edge positions of the shoulder main groove 12 The rib 20 is configured to be recessed inward in the tire radial direction.

  When the tread portion of the pneumatic tire having the tread structure as described above is brought into contact with the ground, a footprint P as shown in FIG. 3 is formed. As shown in part A of FIG. 3, the rubber thickness Hce at both edge positions of the center main groove 11 is made larger than the corresponding reference thickness Ho, so the rubber thickness Hce at the both edge positions of the center main groove 11 is The contact length of each rib row 20 is longer than normal (broken line portion). On the other hand, as shown in part B of FIG. 3, the rubber thickness Hsh at both edge positions of the shoulder main groove 12 is smaller than the corresponding reference thickness Ho, so both edge positions of the shoulder main groove 12 The contact length of each rib row 20 is shorter than the normal length (broken line portion). Thereby, the difference between the contact length of the center main groove 11 and the contact length of the shoulder main groove 12 can be increased, and the frequency of air column resonance noise caused by the main groove 10 can be dispersed. Sound pressure level can be reduced. Further, in the above-described method, since it is not necessary to round the contact shape of the pneumatic tire, it is possible to maintain good non-uniform wear resistance.

In the pneumatic tire, the difference ΔHce between the rubber thickness Hce of each rib row 20 and the corresponding reference thickness Ho at both edge positions of the center main groove 11 is in the range of 0.05 mm to 1.0 mm The difference ΔHsh between the rubber thickness Hsh of each rib row 20 and the corresponding reference thickness Ho at both edge positions of the shoulder main groove 12 is preferably in the range of 0.05 mm to 1.0 mm. As a result, noise performance can be effectively improved while maintaining good partial wear resistance.

Here, if the difference ΔHce is smaller than 0.05 mm, the effect of increasing the contact length is insufficient, and the air column resonance can not be effectively dispersed. If it is larger than 1.0 mm, the rib row is In 10, while the edge portion adjacent to the center main groove 11 is grounded, the other portions are less likely to be grounded, so that uneven wear tends to occur. Also, if the difference ΔHsh is smaller than 0.05 mm, the effect of shortening the contact length is insufficient, and the air column resonance can not be effectively dispersed, and conversely, if it is larger than 1.0 mm, the rib row 10 In this case, the edge portion adjacent to the shoulder main groove 12 is less likely to be in contact with the ground, so that uneven wear tends to occur.

  FIG. 4 shows a main part of a pneumatic tire according to another embodiment of the present invention. The present embodiment relates to a pneumatic tire whose mounting direction to a vehicle is specified, but in FIG. 4 the same symbols are attached to the same items as in FIG. 1 and FIG. . In FIG. 4, 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 a pneumatic tire whose mounting direction to a vehicle is specified, when the distance L11i from the tire equator CL to the center main groove 11 inside the vehicle and the distance L11o from the tire equator CL to the center main groove 11 outside the vehicle are different from each other The difference ΔHce between the rubber thickness Hce of each rib row 20 and the corresponding reference thickness Ho at both edge positions of the center main groove 11 is set to be larger as the center main groove 11 is closer to the tire equator CL Ru. That is, in FIG. 4, the distance L11 o from the tire equator CL to the center main groove 11 on the vehicle outer side is smaller than the distance L11 i from the tire equator CL to the center main groove 11 on the vehicle inner side. The thickness Hce is set to a value larger than the rubber thickness Hce on the inside of the vehicle. Thereby, the contact length of the center main groove 11 on the vehicle outer side near the tire equator CL is relatively lengthened, and the contact length of the center main groove 11 on the vehicle inner side and the contact length of the center main groove 11 on the vehicle outer side Because of the difference between them, the effect of dispersing the air column resonance frequency can be enhanced.

Furthermore, in a pneumatic tire whose mounting direction to a vehicle is specified, the distance L12i from the tire equator CL to the shoulder main groove 12 inside the vehicle and the distance L12o from the tire equator CL to the shoulder main groove 12 outside the vehicle are different from each other In the case, the difference ΔHsh between the rubber thickness Hsh of each rib row 20 and the corresponding reference thickness Ho at the both edge positions of the shoulder main groove 12
Is set to be smaller as the shoulder main groove 12 is closer to the tire equator CL. That is, in FIG. 4, the distance L12 o from the tire equator CL to the shoulder main groove 12 on the vehicle outer side is smaller than the distance L12 i from the tire equator CL to the shoulder main groove 12 on the vehicle inner side. The thickness Hsh is set to a value smaller than the rubber thickness Hsh on the inside of the vehicle. Thereby, the contact length of the shoulder main groove 12 on the vehicle inner side far from the tire equator CL is relatively shortened, and the contact length of the shoulder main groove 12 on the vehicle inside and the contact length of the shoulder main groove 12 on the vehicle outer side Because of the difference between them, the effect of dispersing the air column resonance frequency can be enhanced.

  The distance L11i from the tire equator CL to the center main groove 11 inside the vehicle and the distance L11o from the tire equator CL to the center main groove 11 outside the vehicle are the distances from the tire equator CL to the groove width center position of the center main groove 11 It is. Similarly, a distance L12i from the tire equator CL to the shoulder main groove 12 inside the vehicle and a distance L12o from the tire equator CL to the shoulder main groove 12 outside the vehicle are from the tire equator CL to the groove width center position of the center main groove 12 It is a distance.

  In each of the above-described embodiments, the tread portion has four main grooves extending in the tire circumferential direction, and the main grooves are two shoulder main grooves positioned on the outermost side in the tire width direction and the shoulder main grooves Although the pneumatic tire including the two center main grooves located between is described, the present invention has at least three main grooves extending in the circumferential direction of the tire in the tread portion, and the main grooves include two main grooves. It is possible to apply to a pneumatic tire including a shoulder main groove and at least one center main groove.

  In a pneumatic tire having four main grooves in the tread portion, the rubber thickness Hce of each rib row at both edge positions of the center main groove and the rubber thickness of each rib row at both edge positions of the shoulder main groove By appropriately setting Hsh, it is possible to achieve both the resistance against uneven wear and the noise performance without adversely affecting the drainage property and the steering stability.

  In the case of a pneumatic tire having three main grooves in the tread portion, the dispersion of the frequency of air column resonance noise due to the difference between the contact length of the center main groove and the contact length of the shoulder main groove decreases, and drainage performance is also improved. If each main groove is thickened to secure the sound pressure level of the air column resonance sound becomes large, it becomes disadvantageous from the viewpoint of noise performance. However, if the size of the tire is narrow, even if the main groove is narrowed, the problem of drainage does not become apparent, so arranging three main grooves in the tread is useful in securing block rigidity. It is.

  In the case of a pneumatic tire having five or more main grooves in the tread portion, since each rib row divided by the main grooves becomes thin and the rigidity of each rib row becomes low, it is possible to achieve both noise performance and wear characteristics. However, it is disadvantageous in terms of steering stability. However, when the tire width is wide, the rigidity of the rib row can be sufficiently secured, so arranging five or more main grooves in the tread portion is useful from the viewpoint of drainage.

  A pneumatic tire having a tire size of 225 / 65R17 102V and including a tread portion, a pair of sidewall portions and a pair of bead portions, and in which a mounting direction to a vehicle is specified, at least three tire treads extend in the tire circumferential direction. The main groove has a main groove, and the main groove includes two shoulder main grooves located on the outermost side in the tire width direction and at least one center main groove located between the shoulder main grooves. A plurality of rib rows are divided by the ground contact ends on both sides in the tire width direction, and the rubber thickness (reference thickness) Ho at the widthwise center position of each rib row is set to 8.0 mm, and the rectangular ratio of the tread portion The rubber thickness Hce of each rib row at both edge positions of the center main groove and the rubber thickness Hsh of each rib row at both edge positions of the shoulder main groove are set as shown in Table 1. , Comparison 1-3 and was manufactured tires of Examples 1 to 5.

  The rectangular ratio in Table 1 measures the maximum contact width when the tire is mounted on the major rim of the size described in ETRTO and a load of 100% of the maximum load capacity described in ETRTO based on the load index of the tire is applied. The contact length X1 at the position in the tire width direction corresponding to 80% of the maximum contact width and the contact length X2 at the central position of the maximum contact width are determined and calculated from X1 / X2 × 100%.

  For the positions of the center main groove and shoulder main groove in Table 1, the distance from the tire equator to the ground contact end is measured by the same measurement method as the rectangular ratio, and from the tire equator to the distance from the tire equator to the ground contact It is the ratio (%) of the distance to the groove width center position of the main groove.

  With respect to these test tires, the noise performance and the uneven wear resistance were evaluated by the following test methods, and the results are also shown in Table 1.

Noise performance:
Each test tire is assembled on a wheel of rim size 17 × 7 J and mounted on an SUV vehicle, air pressure is set to 210 kPa, and noise on high frequency range of 500 Hz or more when traveling at a speed of 80 km / h on smooth paved road Carried out. The evaluation results are shown by an index where Conventional Example 1 is 100. The larger the index value, the better the noise performance.

Uneven wear resistance:
Each test tire is assembled to a wheel of rim size 17 × 7 J, mounted on an SUV vehicle, air pressure is set to 210 kPa, and after traveling 16000 km in the city area, the remaining depths of the center main groove and the shoulder main groove are 6 on the tire circumference. It measured in the place and calculated | required the average value of each. Then, the ratio (%) of the remaining groove depth of the center main groove to the remaining groove depth of the shoulder main groove was calculated. The closer this ratio is to 100%, the less uneven wear means.

  As can be seen from Table 1, in comparison with Conventional Example 1, the tires of Examples 1 to 5 were able to improve the noise performance while maintaining good resistance to uneven wear. On the other hand, in the tire of Conventional Example 2, when the number of main grooves was reduced to three, the noise performance was deteriorated due to the relationship of thickening the main grooves. In the tire of Conventional Example 3, although the noise performance was improved by lowering the rectangular ratio, the partial abrasion resistance was reduced accordingly. Further, in the tires of Comparative Examples 1 to 3, the rubber thickness Hce of each rib row at both edge positions of the center main groove and / or the rubber thickness Hsh of each rib row at both edge positions of the shoulder main groove are standard. Although the thickness Ho was changed, good results were not always obtained.

1 tread portion 2 sidewall portion 3 bead portion 10 main groove 11 center main groove 12 shoulder main groove 20 rib row 21 center rib row 22 middle rib row 23 shoulder rib row

Claims (5)

A tread portion extending in the circumferential direction of the tire and forming an annular shape, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed on the tire radial direction inner side of the sidewall portions In the equipped pneumatic tire,
The tread portion has at least three main grooves extending in the tire circumferential direction, and the main grooves are at least positioned between the two shoulder main grooves located on the outermost side in the tire width direction and the shoulder main grooves. Including one center main groove,
A plurality of rib rows are divided by the main groove and the ground contact ends on both sides in the tire width direction, and the center main groove is a center main groove when the rubber thickness at the widthwise center position of each rib row is a reference thickness Ho of the rib rows. The rubber thickness Hce of each rib row at both edge positions of is larger than the corresponding reference thickness Ho, and the rubber thickness Hsh of each rib row at both edge positions of the shoulder main groove is the corresponding reference thickness A pneumatic tire characterized by being smaller than the diameter Ho.   There are four main grooves, and the main groove includes two shoulder main grooves located at the outermost side in the tire width direction and two center main grooves located between the shoulder main grooves. The pneumatic tire according to claim 1, characterized in that: The difference ΔHce between the rubber thickness Hce of each rib row and the corresponding reference thickness Ho at both edge positions of the center main groove is in the range of 0.05 mm to 1.0 mm, both of the shoulder main groove The difference ΔHsh between the rubber thickness Hsh of each rib row at the edge position and the corresponding reference thickness Ho
The tire is in the range of 0.05 mm to 1.0 mm, The pneumatic tire according to claim 1 or 2. In a pneumatic tire whose mounting direction to a vehicle is specified, the distance from the tire equator to the center main groove inside the vehicle and the distance from the tire equator to the center main groove outside the vehicle are different from each other, both edges of the center main groove The difference ΔHce between the rubber thickness Hce of each rib row at the position and the corresponding reference thickness Ho is larger as the center main groove is closer to the tire equator. The pneumatic tire of description. In a pneumatic tire whose mounting direction to a vehicle is specified, the distance from the tire equator to the shoulder main groove inside the vehicle and the distance from the tire equator to the shoulder main groove outside the vehicle are different from each other. The difference ΔHsh between the rubber thickness Hsh of each rib row and the corresponding reference thickness Ho at the position is smaller as the shoulder main groove is closer to the tire equator. The pneumatic tire of description.

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