JP2013180637A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire in which wet performance, dry performance and wear performance can be improved at favorable balance.SOLUTION: A pneumatic tire in which the mounting direction of tire front and back sides when mounted to a vehicle is designated includes a plurality of main grooves 10 extending in a tire circumferential direction in a tread. At least one row of continued lands 11 to 13 continuously extending in a tire circumferential direction while being held by a pair of the main grooves 10 is segmented, and a plurality of lug grooves are formed in the continuous land each having one end opened to the main groove 10 and the other end terminated in the continuous land. When the continuous land is segmented with a center position C in the width direction of the continuous land as a border into a vehicle inside region and a vehicle outside region, a groove area ratio Sin the vehicle inside region of the continuous land is controlled to be larger than a groove area ratio Sin the vehicle outside region of the continuous land. The continuous land is constituted of a first rubber layer R1 at the center side of the land and a second rubber layer R2 at both end sides of the land in which the hardness of the second rubber layer R2 at 20°C is controlled to be higher than the hardness of the first rubber layer R1 at 20°C.

Description

  The present invention relates to a pneumatic tire in which the mounting direction of the tire front and back is specified when the vehicle is mounted, and more particularly to a pneumatic tire that can improve wet performance, dry performance, and wear performance in a well-balanced manner.

  In recent years, with the improvement in vehicle performance, pneumatic tires have a high balance of dry performance, including high-speed lane changeability and dry braking performance, and wet performance, including handling stability on wet road surfaces and wet braking performance. There is a strong demand for improvement.

  Conventionally, in a pneumatic tire, a plurality of main grooves extending in the tire circumferential direction are provided in the tread portion, and a land portion extending in the tire circumferential direction is defined by these main grooves, and the tire width direction with respect to the land portion A lug groove and a sipe extending in the direction are provided (for example, see Patent Document 1). In such a pneumatic tire, it is necessary to increase lug grooves and sipes in order to further improve the wet performance.

  However, increasing lug grooves and sipes in the tread part causes a decrease in rigidity of the land part and non-uniform rigidity in the same land part, resulting in a problem that the dry performance and wear performance of the pneumatic tire deteriorate. There is.

JP 2010-247549 A

  An object of the present invention is to provide a pneumatic tire that can improve wet performance, dry performance, and wear performance in a well-balanced manner.

In order to achieve the above object, a pneumatic tire of the present invention is a pneumatic tire in which a tire front and back mounting direction is specified when a vehicle is mounted, and a plurality of main grooves extending in the tire circumferential direction are provided in a tread portion, A continuous land portion of at least one row extending continuously in the tire circumferential direction while being sandwiched by the main groove of the tire. One end of the continuous land portion is open to the main groove and the other end is terminated in the continuous land portion. A plurality of lug grooves are formed, and the continuous land portion is divided into a vehicle inner region and a vehicle outer region with a center position in the width direction of the continuous land portion as a boundary, and the groove in the vehicle inner region of the continuous land portion The area ratio S _in is made larger than the groove area ratio S _{out in} the vehicle outside region of the continuous land portion, and the continuous land portion is in contact with the first rubber layer disposed on the center side in the width direction on the ground contact surface. A second rubber layer disposed on both ends of the width direction on the ground. The hardness of the second rubber layer at 20 ° C. is higher than the hardness of the first rubber layer at 20 ° C.

In the present invention, in the pneumatic tire in which the mounting direction of the tire front and back is specified when the vehicle is mounted, at least one row of continuous land portions is defined in the tread portion, and one end of the continuous land portion is open to the main groove. A plurality of lug grooves whose ends terminate in the continuous land portion are provided, and the groove area ratio Sin _in the vehicle inner region of the continuous land portion is larger than the groove area ratio _{Sout in} the vehicle outer region of the continuous land portion. By doing so, both wet performance and dry performance are achieved. Here, in order to further improve the wet performance, it is necessary to increase the number of lug grooves. However, if this is done, the dry performance deteriorates due to a decrease in land rigidity, and the wear performance deteriorates due to uneven land rigidity. There is a fear. In contrast, the continuous land portion is composed of a first rubber layer disposed on the center side in the width direction on the ground surface and a second rubber layer disposed on both ends in the width direction on the ground surface, 2 By making the hardness of the rubber layer 20 ° C. higher than the hardness of the first rubber layer 20 ° C., it is possible to suppress the deterioration of the land portion rigidity and the unevenness of the land portion rigidity, and to improve the dry performance and wear performance. Deterioration can be avoided. Therefore, according to the said structure, it becomes possible to improve wet performance, dry performance, and abrasion performance with sufficient balance.

In the present invention, the width W _in the ground contact surface of the second rubber layer in the vehicle inner region of the continuous land portion is made larger than the width W _out of the ground contact surface of the second rubber layer in the vehicle outer region of the continuous land portion. Is preferred. In other words, the width W _in the second rubber layer in the vehicle inner side area of the groove area ratio S _in a relatively high open land portion is relatively large, the groove area ratio S _out is relatively low continuous land portions vehicle By making the width W _out of the second rubber layer in the outer region relatively small, the uniformity of the land portion rigidity is promoted, so that the dry performance and the wear performance can be improved.

The width W of the ground surface of the continuous land portion, setting the range of the width W _in the 0.15 × W~0.35 × W of the ground surface of the second rubber layer in the vehicle inner side region of a continuous land portion and, the width W _out of the ground surface of the second rubber layer in the vehicle outer side region of a continuous land portion is preferably set in a range of 0.05 × W~0.25 × W. Thereby, since uniformity of land part rigidity is accelerated | stimulated, dry performance and abrasion performance can be improved.

Further, the width W _in the with respect to the tire width direction of the length L _in the arranged in the vehicle interior region of the continuous land portion lug grooves, the ground plane of the second rubber layer in the vehicle inner side region of a continuous land portion 0 Set to the range of 5 × L _{in to} 1.0 × L _in , and the vehicle outer side of the continuous land portion with respect to the length L _out in the tire width direction of the lug groove arranged in the vehicle outer region of the continuous land portion The width W _out of the second rubber layer on the contact surface in the region is preferably set in the range of 0.5 × L _{out to} 1.0 × L _out . Thereby, since uniformity of land part rigidity is accelerated | stimulated, dry performance and abrasion performance can be improved.

In the present invention, defines a continuous land portion of the plurality of rows in the tread portion, the difference between the groove area ratio S _out at the groove area ratio S _in the vehicle outer side area of the vehicle inner area, which is calculated for each successive land portions ΔS were different from each other in a continuous land portion of the plurality of columns, the ground plane of the second rubber layer in a width W _in the vehicle outer side region of the ground surface of the second rubber layer in the vehicle inner side region to be calculated for each successive land portions The ratio W _in / W _out to the width W _out of the plurality of rows is made different in the plurality of rows of continuous land portions so that the magnitude relationship of the difference ΔS and the magnitude relationship of the ratio W _in / W _{out in the} rows of consecutive land portions are matched. It is preferable. As a result, even when the difference ΔS between the groove area ratio S _in and the groove area ratio S _out is different from each other in a plurality of rows of continuous land portions, the land portion rigidity is appropriately uniformed. Performance and wear performance can be improved.

  In the present invention, each dimension is measured under the tire static load radius measurement conditions defined by the standard on which the tire is based. The groove area ratio is a ratio (%) of the total area of the groove portions in each region to the total area (including the land portion and the groove portion) of each region of the continuous land portion. The hardness at 20 ° C. is durometer hardness measured using an A type durometer defined in JIS-K6253.

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. It is an expanded sectional view which shows the tread part of FIG. It is a top view which shows the modification of the continuous land part in this invention.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. 1 to 3 show 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. 1 to 3, 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.

  As shown in FIG. 1, the pneumatic tire of the present embodiment includes a tread portion 1 that extends in the tire circumferential direction and has an annular shape, and a pair of sidewall portions 2, 2 disposed on both sides of the tread portion 1. And a pair of bead portions 3 and 3 disposed inside the sidewall portion 2 in the tire radial direction.

  A two-layer carcass layer 4 is mounted between the pair of bead portions 3 and 3. The carcass layer 4 includes a plurality of reinforcing cords extending in the tire radial direction, and is folded from the inside of the tire to the outside around the bead core 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. These belt layers 7 include a plurality of reinforcing cords inclined with respect to the tire circumferential direction, and are arranged so that the reinforcing cords cross each other between the layers. In the belt layer 7, the inclination angle of the reinforcing cord with respect to the tire circumferential direction is set in a range of, for example, 10 ° to 40 °. A steel cord is preferably used as the reinforcing cord of the belt layer 7. For the purpose of improving high-speed durability, at least one belt cover layer 8 in which reinforcing cords are arranged at an angle of, for example, 5 ° or less with respect to the tire circumferential direction is disposed on the outer peripheral side of the belt layer 7. Yes. As the reinforcing cord of the belt cover layer 8, an organic fiber cord such as nylon or aramid is preferably used.

  In addition, although the tire internal structure mentioned above shows the typical example in a pneumatic tire, it is not limited to this.

  As shown in FIG. 2, four main grooves 10 extending in the tire circumferential direction are formed in the tread portion 1, and three rows of continuous land portions (ribs) are formed in the central region of the tread portion 1 by the main grooves 10. 11-13 are partitioned. Each of the continuous land portions 11 to 13 extends continuously in the tire circumferential direction while being sandwiched between the pair of main grooves 10 and 10. Each of the continuous land portions 11 to 13 has a plurality of lug grooves 14 having one end opened in the main groove 10 and the other end terminating in the continuous land portions 11 to 13 at intervals in the tire circumferential direction. Is formed. The groove width and groove depth of the lug groove 14 are not particularly limited, and include, for example, narrow grooves having a groove width of 1 mm or less.

When the continuous land portions 11 to 13 are divided into a vehicle inner region and a vehicle outer region with the center position C in the width direction as a boundary, the continuous land portions 11 to 13 in the vehicle inner region The groove area ratio S _in is larger than the groove area ratio S _{out in} the vehicle outside region of the continuous land portions 11 to 13. In FIG. 2, the relationship of S _in > S _out is satisfied by relatively increasing the lug groove 14 located inside the vehicle relative to the center position C. The groove area ratio S _in is preferably set in the range of 5% to 20%, and the groove area ratio S _out is preferably set in the range of 0% to 10%. The difference ΔS (S _in −S _out ) between the two is 3 It is preferable to set in the range of 10% to 10%. In addition, although it is preferable to arrange the lug grooves 14 on both sides of the center position C in the continuous land portions 11 to 13, the lug grooves 14 may be arranged only in the vehicle inner side region as shown in FIG.

  On the other hand, a land portion 21 is disposed in a shoulder region outside the vehicle of the tread portion 1, and a plurality of lug grooves 22 extending in the tire width direction are formed in the land portion 21 at intervals in the tire circumferential direction. . The lug groove 22 crosses the land portion 21. Therefore, the land portion 21 is partitioned into a plurality of blocks 23 by these lug grooves 22. A land portion 31 is disposed in a shoulder region inside the vehicle of the tread portion 1, and a plurality of lug grooves 32 extending in the tire width direction are formed in the land portion 31 at intervals in the tire circumferential direction. The lug groove 32 does not cross the land portion 31. That is, the lug groove 32 is not in communication with the main groove 10.

  In the pneumatic tire, as shown in FIG. 3, each of the continuous land portions 11 to 13 includes a rubber layer R <b> 1 (first rubber layer) disposed on the center side in the width direction on the ground surface and a ground surface. It is comprised from the rubber layer R2 (2nd rubber layer) arrange | positioned at the both ends of the width direction. The hardness of the rubber layer R2 at 20 ° C. is higher than the hardness of the rubber layer R1 at 20 ° C. For example, the hardness of the rubber layer R1 at 20 ° C. is set in a range of 60 to 68, and the hardness of the rubber layer R2 at 20 ° C. is set in a range of 70 to 75. In addition to the above-described hardness relationship, it is desirable that the breaking strength at 20 ° C. of the rubber layer R2 is higher than the breaking strength at 20 ° C. of the rubber layer R1.

  In FIG. 3, the rubber layer R <b> 1 is a matrix, and the rubber layer R <b> 2 is locally arranged along the groove wall of the main groove 10. Such an arrangement is facilitated by locally disposing the rubber layer R2 at the main groove forming position of the unvulcanized tire so that the main groove forming bone is pushed into the rubber layer R2 in the mold. Can be formed.

As described above, in the pneumatic tire in which the mounting direction of the tire front and back when the vehicle is mounted is specified, the tread portion 1 is divided into at least one row of continuous land portions 11 to 13, and one end is formed on the continuous land portions 11 to 13. a plurality of lug grooves 14 and the other end opened to the main groove 10 terminates in said continuous land portions 11 to 13 provided, the continuous groove area ratio S _in in the vehicle inner side region of a continuous land portions 11 to 13 By making it larger than the groove area ratio S _{out in} the vehicle outer area of the land, it is represented by wet performance represented by steering stability and wet braking performance on wet road surface, high-speed lane change performance and dry braking performance. The dry performance can be made compatible. In other words, wet performance is improved by relatively increasing the groove area ratio Sin _in the vehicle inner region, while dry performance is improved by relatively decreasing the groove area ratio _Sout in the vehicle outer region. can do.

  Here, in order to further improve the wet performance, it is necessary to increase the number of lug grooves 14 or to increase the size of the lug grooves 14, but if this is done, the rigidity of the continuous land portions 11 to 13 decreases and the dry performance Further, there is a risk that the rigidity of the continuous land portions 11 to 13 becomes uneven and the wear performance deteriorates. On the other hand, the continuous land portions 11 to 13 are composed of a rubber layer R1 disposed on the center side in the width direction on the ground surface and a rubber layer R2 disposed on both ends in the width direction on the ground surface. By making the hardness of the rubber layer R2 at 20 ° C. higher than the hardness of the rubber layer R1 at 20 ° C., it is possible to suppress a decrease in rigidity and unevenness of the continuous land portions 11 to 13, and to improve the dry performance and wear performance. Deterioration can be avoided. Thereby, wet performance, dry performance, and wear performance can be improved in a well-balanced manner.

In the pneumatic tire described above, the width W _in (W1 _in , W2 _in , W3 _in ) at the contact surface of the rubber layer R2 in the vehicle inner region of the continuous land portions 11 to 13 is in the vehicle outer region of the continuous land portions 11 to 13. It is set to be larger than the width W _out (W1 _out , W2 _out , W3 _out ) at the ground contact surface of the rubber layer R2. That is, since the rigidity of the continuous land portions 11 to 13 is reduced in proportion to the groove area ratios S _in and S _out , the rubber layer in the vehicle inner region of the continuous land portions 11 to 13 having a relatively high groove area ratio S _in. the width W _in the R2 was relatively large, by a width W _out of the rubber layer R2 in the vehicle outer side area of the groove area ratio S _out is relatively low continuous land portions 11 to 13 relatively small, continuous land The rigidity of the parts 11 to 13 can be made more appropriate and the dry performance and wear performance can be improved.

More specifically, the width at the ground contact surface of the rubber layer R2 in the vehicle inner region of the continuous land portions 11 to 13 with respect to the width W (W1, W2, W3) at the ground contact surface of the continuous land portions 11 to 13. W _in (W 1 _in , W 2 _in , W 3 _in ) is set in the range of 0.15 × W to 0.35 × W, and the width of the rubber layer R2 on the ground contact surface in the vehicle outer region of the continuous land portions 11 to 13 W _out (W1 _out , W2 _out , W3 _out ) is preferably set in a range of 0.05 × W to 0.25 × W. Thereby, since the uniformity of the rigidity of the continuous land parts 11-13 is accelerated | stimulated, dry performance and abrasion performance can be improved.

Here, if the ratio W _in / W is less than 0.15, the effect of compensating for the decrease in rigidity becomes insufficient. Conversely, if the ratio W _in / W exceeds 0.35, the rigidity at the vehicle inner end of the continuous land portion becomes excessive, and the continuous land The rigidity balance with the central part of the part is lost, and the effect of improving the dry performance and wear performance becomes insufficient. Further, if the ratio W _out / W is less than 0.05, the effect of compensating for the decrease in rigidity becomes insufficient. Conversely, if the ratio W _out / W exceeds 0.25, the rigidity of the vehicle outer end of the continuous land portion becomes excessive, and the continuous land portion The rigidity balance with the central portion of the steel is lost, and the effect of improving the dry performance and wear performance becomes insufficient.

Further, the vehicle of the continuous land portions 11 to 13 with respect to the length L _in (L1 _in , L2 _in , L3 _in ) _in the tire width direction of the lug groove 14 arranged in the vehicle inner side region of the continuous land portions 11 to 13. The width W _in (W1 _in , W2 _in , W3 _in ) of the rubber layer R2 in the inner region is set _in a range of 0.5 × L _{in to} 1.0 × L _in and the continuous land portions 11 to 13 are set. Of the lug groove 14 arranged in the vehicle outer region of the vehicle in the tire width direction with respect to the length L _out (L1 _out , L2 _out , L3 _out ) of the rubber layer R2 in the vehicle outer region of the continuous land portions 11 to 13 The width W _out (W1 _out , W2 _out , W3 _out ) on the ground is preferably set in the range of 0.5 × L _{out to} 1.0 × L _out . Thereby, since the uniformity of the rigidity of the continuous land parts 11-13 is accelerated | stimulated, dry performance and abrasion performance can be improved.

Here, if the ratio W _in / L _in is less than 0.5, the effect of compensating for the decrease in rigidity becomes insufficient, while if it exceeds 1.0, the effect of compensating for the decrease in rigidity becomes excessive, and the center of the continuous land portion is excessive. The rigidity balance with the portion may be lost, and the effect of improving dry performance and wear performance may be insufficient. In addition, if the ratio W _out / L _out is less than 0.5, the effect of compensating for the decrease in rigidity becomes insufficient. Conversely, if the ratio W _out / L _out exceeds 1.0, the effect of compensating for the decrease in rigidity becomes excessive. There is a risk that the effect of improving dry performance and wear performance may be insufficient.

In the above-described pneumatic tire, the groove area ratio S _in in the vehicle inner side region to be calculated for each successive land portions _{11~13 (S1 in, S2 in,} S3 in) the groove area ratio S _out of the vehicle outer side region The difference ΔS from (S1 _out , S2 _out , S3 _out ) can be made different from each other in the plurality of rows of continuous land portions 11 to 13. In other words, the difference .DELTA.S1 continuous land portion 11 is calculated from the equation ΔS1 = S1 _in -S1 _out, the difference [Delta] S2 of the continuous land portion 12 is calculated from the equation ΔS2 = S2 _in -S2 _out, the difference between the continuous land portion 13 ΔS3 is calculated from the equation: ΔS3 = S3 _in −S3 _out , and these differences ΔS1 to ΔS3 can be set to different values depending on the required characteristics of the tread portion 1.

In such a case, the width W _in the ground contact surface of the rubber layer R2 in the vehicle inner region calculated for each of the continuous land portions 11 to 13 and the width W _{out in} the ground contact surface of the rubber layer R2 in the vehicle outer region are calculated. The ratio W _in / W _out (W1 _in / W1 _out W2 _in / W2 _out W3 _in / W3 _out ) is made different in the plurality of rows of continuous land portions 11 to 13, and the difference ΔS in the plurality of rows of continuous land portions 11 to 13 It is preferable to match the magnitude relationship between and the ratio W _in / W _out . Thereby, even when the difference ΔS between the groove area ratio S _in and the groove area ratio S _out is different from each other in the plural rows of continuous land portions 11 to 13, the rigidity of the continuous land portions 11 to 13 is uniform. Therefore, dry performance and wear performance can be improved.

In the above-described embodiment, in the pneumatic tire including a plurality of rows of continuous land portions, the groove area ratio S _in is made larger than the groove area ratio S _out for all the continuous land portions and the first rubber having low hardness is used. Although the structure which combined the layer and the 2nd rubber layer of high hardness is applied, such a structure should just be applied to the continuous land part of at least 1 row. Of course, when the above configuration is applied to all the continuous land portions, a remarkable effect can be obtained.

In a pneumatic tire having a tire size of 205 / 55R16 and a mounting direction of the tire front and back when the vehicle is mounted, four main grooves extending in the tire circumferential direction are provided in the tread portion as shown in FIGS. , Partitioning three rows of continuous land portions continuously extending in the tire circumferential direction while being sandwiched between a pair of main grooves, one end of the continuous land portion opening into the main groove, and the other end within the continuous land portion A plurality of terminal lug grooves are provided, and the continuous land portion is divided into a vehicle inner region and a vehicle outer region with the center position in the width direction of the continuous land portion as a boundary, and the groove area in the vehicle inner region of the continuous land portion The ratio S _in (S 1 _in , S 2 _in , S 3 _in ) is made larger than the groove area ratio S _out (S 1 _out , S 2 _out , S 3 _out ) in the vehicle outer region of the continuous land portion, and the continuous land portion is contacted. The first rubber layer placed on the center side in the width direction on the ground and the width on the ground plane The second rubber layer is disposed on both ends of the first rubber layer, the hardness of the second rubber layer at 20 ° C. is higher than the hardness of the first rubber layer at 20 ° C., and the first rubber layer and the second rubber Layer hardness, groove area ratio difference ΔS (ΔS1, ΔS2, ΔS3) of each continuous land portion, width ratio W _in / W _out (W1 _in / W1 _out W2 _in / W2 _out W3 _in / Tires of Examples 1 to 4 in which _W3out ) was set as shown in Table 1 were produced.

  Moreover, the tire of the comparative example 1 which has the same structure as Examples 1-4 except having comprised the continuous land part with the single type rubber layer for the comparison was prepared.

In Examples 1 to 4 and Comparative Example 1, the width W (W1, W2, W3) of each continuous land portion is 30 mm, and the length in the tire width direction of the lug groove arranged in the vehicle inner side region of each continuous land portion L _in (L 1 _in , L 2 _in , L 3 _in ) is 10 mm, and the length L _out (L 1 _out , L 2 _out , L 3 _out ) in the tire width direction of the lug groove arranged in the vehicle outer region of each continuous land portion is It was 7.5 mm.

  These test tires were evaluated for steering stability, wet braking performance, and wear performance by the following test methods, and the results are also shown in Table 1.

Steering stability:
The test tire was assembled on a wheel with a rim size of 16 × 7 JJ and mounted on a test vehicle. A running test on a dry road surface by a test driver was performed under the condition of an air pressure of 250 kPa, and sensory evaluation was performed on the handling stability. The evaluation results are shown as an index with Comparative Example 1 as 100. The larger the index value, the better the steering stability.

Wet braking performance:
The test tire was assembled on a wheel with a rim size of 16 × 7 JJ and mounted on a test vehicle, and a braking test was performed on a wet road surface by a test driver under the condition of an air pressure of 250 kPa. Specifically, the brake was applied from the traveling state at a speed of 100 km / h, and the braking distance was measured. The evaluation results are shown as an index using Comparative Example 1 as 100, using the reciprocal of the measured value. A larger index value means better wet braking performance.

Wear performance:
The test tire is assembled to a wheel with a rim size of 16 x 7 JJ and mounted on a test vehicle. The amount of wear at the tread when the vehicle runs at 20,000 km under the condition of air pressure of 250 kPa is measured, and the wear life (distance) is based on the amount of wear. Estimated. The evaluation results are shown as an index with Comparative Example 1 as 100. A larger index value means better wear performance.

  As shown in Table 1, in comparison with Comparative Example 1, the tires of Examples 1 to 4 can improve steering stability and wear performance on a dry road surface while maintaining good wet braking performance. did it.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Carcass layer 5 Bead core 6 Bead filler 7 Belt layer 8 Belt cover layer 10 Main groove 11, 12, 13 Continuous land part 14 Lug groove R1 1st rubber layer R2 2nd rubber layer

Claims (5)

In a pneumatic tire in which the mounting direction of the tire front and back is specified when the vehicle is mounted, a plurality of main grooves extending in the tire circumferential direction are provided in the tread portion and continuously extending in the tire circumferential direction while being sandwiched between the pair of main grooves. A plurality of lug grooves, one end of which is open to the main groove and the other end of which is terminated in the continuous land portion. The continuous land portion is divided into a vehicle inner region and a vehicle outer region with a central position in the direction as a boundary, and a groove area ratio S _in the vehicle inner region of the continuous land portion is determined in the vehicle outer region of the continuous land portion. The first rubber layer disposed on the center side in the width direction on the ground surface and the second rubber disposed on both ends in the width direction on the ground surface while increasing the groove area ratio S _out. A second rubber layer having a hardness at 20 ° C. of the first rubber layer. A pneumatic tire characterized by having a hardness higher than that at 20 ° C. The width W _in the ground contact surface of the second rubber layer in the vehicle inner region of the continuous land portion is larger than the width W _out of the ground contact surface of the second rubber layer in the vehicle outer region of the continuous land portion. The pneumatic tire according to claim 1. The width W of the ground surface of the continuous land portion, a width W _in a 0.15 × W~0.35 × W of the ground surface of the second rubber layer in the vehicle inner side region of the continuous land portion The width W _out of the ground contact surface of the second rubber layer in the vehicle outer region of the continuous land portion is set in a range of 0.05 × W to 0.25 × W. Item 3. The pneumatic tire according to Item 2. With respect to the tire width direction of the length L _in the arranged lug grooves in the vehicle inner side area of the continuous land portion, a width W _in the in the ground plane of the second rubber layer in the vehicle inner side region of the continuous land portion The continuous land portion is set to a range of 0.5 × L _{in to} 1.0 × L _in , and the length L _out in the tire width direction of the lug groove disposed in the vehicle outer region of the continuous land portion is The width W _out of the ground contact surface of the second rubber layer in the vehicle outside region is set in a range of 0.5 × L _{out to} 1.0 × L _out . Pneumatic tire described in 2. And partitioning the continuous land portion of the plurality of rows in the tread portion, a plurality of difference ΔS between the groove area ratio S _out at the groove area ratio S _in the vehicle outer side area of the vehicle inner area, which is calculated for each successive land portions The width L _in the ground contact surface of the second rubber layer in the vehicle inner region and the ground contact surface of the second rubber layer in the vehicle outer region calculated for each continuous land portion are different from each other in the continuous land portion of the row. were different from each other in a continuous land portion of the plurality of rows ratio W _in / W _out of the width W _out, was coincident with the magnitude relation of the magnitude relationship and the ratio W _in / W _out of the difference ΔS in the continuous land portion of the plurality of rows The pneumatic tire according to any one of claims 1 to 4, wherein:

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