JP5835410B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire in which a tread portion is provided with a center rib located on the tire equator and a plurality of block rows located on both sides thereof, and more specifically, to improve the performance on ice and the performance on snow in a well-balanced manner. It relates to a pneumatic tire that has been made effective.

  In a pneumatic tire, a tread portion is provided with a plurality of circumferential grooves extending in the tire circumferential direction and a plurality of lug grooves extending in the tire width direction, and these circumferential grooves and the lug grooves are provided on the tire equator. A tread pattern in which a center rib located and a plurality of block rows located on both sides of the center rib are defined and a plurality of sipes are provided on each land portion has been proposed (for example, see Patent Documents 1 to 3).

  A pneumatic tire provided with such a tread pattern exhibits desired performance on ice and performance on snow based on circumferential grooves, lug grooves and sipes formed in the tread portion. However, on ice, for example, the sipe subdivided block collapses when stepping on or kicking out, so that traction on the ice can be secured. Is insufficient, and sufficient traction on the snow cannot be secured. Therefore, optimal traction cannot be ensured both on ice and on snow, and it is difficult to improve on-ice performance and on-snow performance at the same time.

JP 2009-120055 A JP 2010-167930 A JP 2010-188778 A

  An object of the present invention is to provide a pneumatic tire capable of improving the performance on ice and the performance on snow in a balanced manner.

In order to achieve the above object, a pneumatic tire according to the present invention includes a tread portion that extends in the tire circumferential direction to form an annular shape, a pair of sidewall portions disposed on both sides of the tread portion, and the sidewall portions. In a pneumatic tire provided with a pair of bead portions arranged on the inner side in the tire radial direction of
In the tread portion, a pair of first circumferential main grooves extending in the tire circumferential direction on both sides of the tire equator, and a pair extending along the tire circumferential direction on the outer side in the tire width direction of each first circumferential main groove. A second circumferential main groove, a plurality of first lug grooves extending from the first circumferential main groove toward the grounding end toward the outer side in the tire width direction, and a pair of first lugs adjacent in the tire circumferential direction A second lug groove extending in the tire width direction between the grooves, a third lug groove extending in the tire width direction between the pair of first lug grooves, and a tire circumferential direction between the pair of first lug grooves A circumferential auxiliary groove extending between the pair of first circumferential main grooves, a center rib is defined between the pair of first circumferential main grooves, and between the first circumferential main groove and the second circumferential main groove. The first block facing both the first circumferential main groove and the second circumferential main groove, the first circumferential main groove and the second circumference An intermediate block row constituted as a repeating unit of the second block to a group of intermediate block consisting of a fifth block faces only one of the direction main grooves is partitioned, the tire width direction of the second circumferential main groove defines a shoulder block row composed of a plurality of shoulder blocks on the outside, the center rib, the intermediate block and Rutotomoni a plurality of sipes extending in the tire width direction in each of the shoulder block,
The second lug groove that divides the first block, the second block, and the third block is bent, and the second lug groove has an inclination direction reversed with respect to the tire width direction at the bending point. It is characterized by.

  In the present invention, an intermediate unit including a group of intermediate blocks including a wide first block and narrow second to fifth blocks as a repeating unit between the first circumferential main groove and the second circumferential main groove. By forming the block row, the second block to the fifth block are relatively low in rigidity and easy to fall down while sufficiently securing traction on snow based on the first block having relatively high rigidity. Therefore, sufficient traction on ice can be secured. As a result, it is possible to improve the performance on ice and the performance on snow in a well-balanced manner.

  In the present invention, the maximum width W1 in the tire width direction of the first block is preferably 90% to 100% of the total width W2 of the intermediate block row. Thereby, the traction on snow can be increased without impairing snow removal performance.

  In the group of intermediate blocks, the total surface area S1 of the tread surfaces of the second block and the third block adjacent to the first block and the total surface area of the tread surfaces of the fourth block and the fifth block adjacent to the second block and the third block. It is preferable that S2 has a relationship of S1> S2. In particular, the total surface area S1 and the total surface area S2 are preferably in a relationship of 1.2 ≦ S1 / S2 ≦ 1.5. By providing a difference in the amount of fall in the group of intermediate blocks based on such a relationship, the existence of the first block having relatively high rigidity is emphasized, and the performance on ice and the performance on snow are effectively improved. be able to.

  The maximum width G1 in the intermediate block row of the first lug grooves, the maximum width G2 in the intermediate block row of the second lug grooves that divides the first block, the second block, and the third block, and the second block The maximum width G3 in the intermediate block row of the third lug groove that divides the third block from the fourth block and the fifth block is 1.0 <G1 / G2 ≦ 2.5, 1.0 <G1. It is preferable that /G3≦2.5. Thereby, the presence of the first block having relatively high rigidity can be emphasized, and the performance on ice and the performance on snow can be effectively improved.

The second lug grooves for dividing the first block and the second block and the third block is bent, and the second lug grooves shall inclination direction is reversed with respect to the tire width direction as a boundary bending point. Thereby, the traction on snow can be increased.

  Moreover, it is preferable that inclination | tilt angle (theta) 1 with respect to the tire width direction of the both-sides part of the bending point of a 2nd lug groove is 10 degrees-30 degrees. Thereby, on-snow performance can be improved without impairing snow removal performance, and the effect of reducing outside noise can also be expected.

  The third lug groove that separates the second block and the third block from the fourth block and the fifth block is preferably bent. In particular, it is preferable that the third lug groove has the inclination direction reversed with respect to the tire width direction at the bending point. Thereby, the traction on snow can be increased.

  Moreover, it is preferable that the inclination | tilt angle (theta) 2 with respect to the tire width direction of the both sides of the bending point of a 3rd lug groove is 10 degrees-30 degrees. Thereby, on-snow performance can be improved without impairing snow removal performance, and the effect of reducing outside noise can also be expected.

In the present invention, the snow traction index STI represented by the following formula (1) is preferably 180 or more in order to sufficiently ensure the performance on snow.
STI = −6.8 + 2202ρg + 672ρs + 7.6Dg (1)
However, ρg: groove density (mm / mm ² ) = gross length of the extended component in the tire width direction of the groove (mm)
/ Total area of ground contact area (mm ² )
ρs: sipe density (mm / mm ² ) = total length of sipe extension components in the tire width direction
(Mm) / Total area of ground contact area (mm ² )
Dg: Average groove depth (mm)

  In the present invention, the contact area of the tread portion is the contact width in the tire axial direction measured when a normal load is applied by placing the tire on a regular rim and filling the regular internal pressure vertically on a plane. Specified based on. The ground contact edge is the outermost position in the tire axial direction of the ground contact region. The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based, for example, a standard rim for JATMA, “Design Rim” for TRA, or ETRTO. Then, “Measuring Rim” is set. “Regular internal pressure” is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire is based. The maximum air pressure is JATMA, and the table “TIRE ROAD LIMITS AT VARIOUS” is TRA. The maximum value described in “COLD INFRATION PRESURES”, “INFLATION PRESURE” for ETRTO, but 180 kPa when the tire is a passenger car. “Regular load” is a load determined by each standard for each tire in the standard system including the standard on which the tire is based. The maximum load capacity is JATMA, and the table “TIRE ROAD LIMITS AT VARIOUS” The maximum value described in “COLD INFORATION PRESSURES” is “LOAD CAPACITY” if it is ETRTO, but if the tire is a passenger car, the load is equivalent to 88% of the load.

It is meridian sectional drawing which shows the pneumatic tire which consists of embodiment of this invention. FIG. 2 is a development view showing a tread pattern of the pneumatic tire of FIG. 1. It is a top view which shows a center rib and an intermediate | middle block row | line with a dimension line. It is a top view which shows a center rib and an intermediate | middle block row | line with another dimension line. It is a top view which shows a center rib and an intermediate | middle block row | line with another dimension line further.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. 1 to 5 show a pneumatic tire according to an embodiment of the present invention.

  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 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, the tread portion 1 includes a pair of first circumferential main grooves 11 extending along the tire circumferential direction on both sides of the tire equator CL, and tire widths of the first circumferential main grooves 11. A pair of second circumferential main grooves 12 extending along the tire circumferential direction on the outer side in the direction, and a plurality of second circumferential grooves extending from the first circumferential main groove 11 toward the outer side in the tire width direction to at least the ground contact edge E. Tire width between one lug groove 21, second lug groove 22 extending in the tire width direction between a pair of first lug grooves 21, 21 adjacent in the tire circumferential direction, and a pair of first lug grooves 21, 21 A third lug groove 23 extending in the direction and a circumferential auxiliary groove 13 extending in the tire circumferential direction are formed between the pair of first lug grooves 21, 21. The second lug groove 22 merges with the first lug groove 21 in the vicinity of the second circumferential main groove 12, and the third lug groove 23 extends at least to the ground contact edge E toward the outer side in the tire width direction. Further, this pneumatic tire is a tire in which the rotation direction R is specified, but the first lug groove 21 is inclined in the direction opposite to the rotation direction R from the tire equator CL side toward the outer side in the tire width direction. The first circumferential main groove 11 and the second circumferential main groove 12 are grooves having a groove width in the range of 7 mm to 10 mm and a groove depth in the range of 8.0 mm to 12.0 mm. On the other hand, the circumferential auxiliary groove 13 is narrower than the first circumferential main groove 11 and the second circumferential main groove 12, has a groove width in the range of 3 mm to 5 mm, and has a groove depth of 7.0 mm to 11. It is a groove in the range of 0 mm.

  Thereby, in the tread portion 1, the center rib 30 is defined between the pair of first circumferential main grooves 11, 11, and between the first circumferential main groove 11 and the second circumferential main groove 12. Includes an intermediate block row 40 including a group of five intermediate blocks 41 including a first block 41A, a second block 41B, a third block 41C, a fourth block 41D, and a fifth block 41E as a repeating unit. A shoulder block row 50 including a plurality of shoulder blocks 51 is defined on the outer side in the tire width direction of the directional main groove 12. A plurality of sipes 32, 42, 52 extending in the tire width direction are formed on the center rib 30, the intermediate block 41 of the intermediate block row 40, and the shoulder block 51 of the shoulder block row 50, respectively. These sipes 32, 42 and 52 may extend linearly or may extend in a zigzag manner.

  In the pneumatic tire, the intermediate block row 40 includes a group of five intermediate blocks 41 including a first block 41A, a second block 41B, a third block 41C, a fourth block 41D, and a fifth block 41E as a repeating unit. Yes. More specifically, the first block 41 </ b> A has an outer row composed of the second block 41 </ b> B and the fourth block 41 </ b> D located on the outer side in the tire width direction from the circumferential auxiliary groove 13 and the tire width direction from the circumferential auxiliary groove 13. A wide structure that is arranged so as to straddle the inner row of the third block 41C and the fifth block 41E located on the inner side and faces both the first circumferential main groove 11 and the second circumferential main groove 12 have. Further, the second block 41B and the third block 41C adjacent to the first block 41A have a narrow structure that faces only one of the first circumferential main groove 11 and the second circumferential main groove 12. Have. Further, the fourth block 41D and the fifth block 41E adjacent to the second block 41B and the third block 41C face only one of the first circumferential main groove 11 and the second circumferential main groove 12. It has a narrow structure. In particular, the second block 41B to the fifth block 41E have a substantially parallelogram shape, whereas the first block 41A has a substantially trapezoidal shape.

  In the pneumatic tire described above, an intermediate block including a first block 41A having a wide width and second blocks 41B to 41E having a narrow width between the first circumferential main groove 11 and the second circumferential main groove 12. Since the intermediate block row 40 including the group of 41 as a repeating unit is formed, traction on snow can be sufficiently secured based on the first block 41A having relatively high rigidity. On the other hand, traction on ice can be sufficiently ensured based on the second block 41B to the fifth block 41E, which have relatively low rigidity and are likely to fall down. That is, since the group of the intermediate blocks 41 includes the first block 41A that contributes to the improvement on the performance on snow and the second block 41B to the fifth block 41E that contributes to the improvement on the performance on ice, the performance on the ice and the performance on the snow are well balanced. It becomes possible to improve.

  In the pneumatic tire, as shown in FIG. 3, the maximum width W1 in the tire width direction of the first block 41A is preferably 90% to 100% of the total width W2 of the intermediate block row 40. Thereby, the traction on snow can be increased without impairing snow removal performance. If the maximum width W1 of the first block 41A is smaller than 90% of the total width W2 of the intermediate block row 40, the effect of increasing the traction on the snow is reduced, and conversely if it is larger than 100% of the full width W2, the first circumferential direction Since the snow clogged in the main groove 11 or the second circumferential main groove 12 is difficult to be discharged, the effect of improving the performance on snow is reduced. The full width W2 of the intermediate block row 40 means the total width of the intermediate block row 40 specified by the other intermediate blocks 41 excluding the first block 41A.

  In the group of intermediate blocks 41, the total surface area S1 of the tread surfaces of the second block 41B and the third block 41C and the total surface area S2 of the tread surfaces of the fourth block 41D and the fifth block 41E are in a relationship of S1> S2. Good to have. In particular, the total surface area S1 and the total surface area S2 are preferably in a relationship of 1.2 ≦ S1 / S2 ≦ 1.5. By providing a difference in the amount of collapse among the group of intermediate blocks 41 based on such a relationship, the existence of the first block 41A having relatively high rigidity is emphasized, and the performance on ice and the performance on snow are effectively improved. Can be improved. If the ratio S1 / S2 is smaller than 1.2, the difference in rigidity between the blocks 41B and 41C and the blocks 41D and 41E is reduced, and a difference in the amount of collapse cannot be provided, and conversely it is larger than 1.5. And the rigidity of 4th block 41D and 5th block 41E falls too much, and wear performance falls. In addition, the surface area of the tread of each block 41B-41E is the area (including sipe area) of the area | region enclosed by the outline of the tread of each block 41B-41E.

  As shown in FIG. 4, the maximum width G1 of the first lug groove 21 in the intermediate block row 40 and the middle of the second lug groove 22 that divides the first block 41A, the second block 41B, and the third block 41C. The maximum width G2 in the block row 40, and the maximum width G3 in the intermediate block row 40 of the third lug groove 23 that divides the second block 41B, the third block 41C, the fourth block 41D, and the fifth block 41E. Are preferably in a relationship of 1.0 <G1 / G2 ≦ 2.5 and 1.0 <G1 / G3 ≦ 2.5. Thus, by enlarging the maximum width G1 of the first lug groove 21, the effect of the first block 41A having relatively high rigidity is emphasized, and the performance on ice and the performance on snow are effectively improved. Can do. However, if the ratio G1 / G2 and the ratio G1 / G3 are larger than 2.5, the second lug groove 22 and the third lug groove 23 are excessively narrowed, so that the performance on snow is reduced, or the first lug The performance on ice falls because the groove | channel 21 becomes large too much.

  In the pneumatic tire, the second lug groove 22 that divides the first block 41A, the second block 41B, and the third block 41C is bent halfway. More specifically, as shown in FIG. 5, the second lug groove 22 has its inclination direction reversed with respect to the tire width direction (direction perpendicular to the tire equator CL) with the bending point P1 as a boundary. In particular, the second lug groove 22 is preferably bent so as to be convex in the direction opposite to the designated rotation direction R. By providing such a bent structure to the second lug groove 22, traction on snow can be increased.

  The inclination angle θ1 with respect to the tire width direction of both side portions of the bending point P1 of the second lug groove 22 is preferably 10 ° to 30 °. Thereby, on-snow performance can be improved without impairing snow removal performance. If the inclination angle θ1 is smaller than 10 °, the effect of increasing the traction on the snow is reduced, and conversely if it is larger than 30 °, the snow drainage performance is lowered. Further, when the second lug groove 22 is bent, the air column resonance generated in the tire equator CL side groove is prevented from being released to the outside in the tire width direction, and the effect of reducing outside noise can be obtained. .

  Similarly, the 3rd lug groove 23 which divides the 2nd block 41B and the 3rd block 41C, and the 4th block 41D and the 5th block 41E is bent on the way. More specifically, as shown in FIG. 5, the third lug groove 23 has its inclination direction reversed with respect to the tire width direction (direction perpendicular to the tire equator CL) with the bending point P2 as a boundary. In particular, the third lug groove 23 is preferably bent so as to be convex in the direction opposite to the designated rotation direction R. By providing such a bent structure to the third lug groove 23, the traction on snow can be increased.

  The inclination angle θ2 with respect to the tire width direction of both side portions of the bending point P2 of the third lug groove 23 is preferably 10 ° to 30 °. Thereby, on-snow performance can be improved without impairing snow removal performance. If the inclination angle θ2 is smaller than 10 °, the effect of increasing the traction on the snow is reduced, and conversely if it is larger than 30 °, the snow drainage performance is lowered. Further, when the third lug groove 23 is bent, the air column resonance generated in the groove on the tire equator CL side is prevented from being released to the outside in the tire width direction, and an effect of reducing outside noise can be obtained. .

In a pneumatic tire having a tread portion, a pair of sidewall portions, and a pair of bead portions with a tire size of 225 / 65R17 102Q, a pair of tires extending along the tire circumferential direction on both sides of the tire equator in the tread portion. A first circumferential main groove, a pair of second circumferential main grooves extending along the tire circumferential direction on the outer side in the tire width direction of each first circumferential main groove, and the tire width direction from the first circumferential main groove A plurality of first lug grooves extending to the grounding end toward the outside, a second lug groove extending in the tire width direction between a pair of first lug grooves adjacent in the tire circumferential direction, and a pair of first lugs A third lug groove extending in the tire width direction between the lug grooves and a circumferential auxiliary groove extending in the tire circumferential direction between the pair of first lug grooves are provided, and the pair of first circumferential main grooves are mutually connected. A center rib is defined between the first circumferential main groove and the second circumferential main groove. Between the first block facing both the first circumferential main groove and the second circumferential main groove and the second block facing only one of the first circumferential main groove and the second circumferential main groove. An intermediate block row including a group of intermediate blocks consisting of a fifth block as a repeating unit is partitioned, a shoulder block row consisting of a plurality of shoulder blocks is defined on the outer side in the tire width direction of the second circumferential main groove, a center rib, Tires of Examples 1 to 18 and Reference Example 1 in which a plurality of sipes extending in the tire width direction were provided on each of the intermediate block and the shoulder block were manufactured.

In Examples 1 to 18 and Reference Example 1 , the maximum width W1 of the first block (ratio to the total width W2 of the intermediate block row), the sum S1 of the surface areas of the tread surfaces of the second block and the third block, the fourth block, and the fifth block The ratio S1 / S2 of the total surface area S2 of the treads of the block, the ratio G1 / G2 of the maximum width G1 of the first lug groove and the maximum width G2 of the second lug groove, the maximum width G1 of the first lug groove and the third The ratio G1 / G3 with the maximum width G3 of the lug groove, the inclination angle θ1 of the second lug groove, and the inclination angle θ2 of the third lug groove were set as shown in Tables 1 and 2.

  For comparison, a conventional tire having the same structure as that of Example 1 is prepared except that each intermediate block row is composed of two rows of block rows divided by circumferential auxiliary grooves extending in the tire circumferential direction. did. The tire of the conventional example corresponds to the pneumatic tire described in Japanese Patent Application Laid-Open No. 2009-120055.

  About these test tires, the driving performance on ice and the driving performance on snow were evaluated by the following test methods, and the results are also shown in Tables 1 and 2. Each evaluation was performed under the condition that the test tire was mounted on a wheel with a rim size of 17 × 7 J and mounted on a front-wheel drive vehicle with a displacement of 2000 cc, and the air pressure after warm-up was 220 kPa.

Driving performance on ice:
About each test tire, the climbing test on the same conditions on ice was implemented, and the travel time at the time of drive | working a predetermined area was measured. The evaluation results are shown as an index with the conventional example being 100, using the reciprocal of the measured value. The larger the index value, the better the driving performance on ice.

Snow drive performance:
About each test tire, the climbing test on the same conditions on snow was implemented, and the running time at the time of drive | working a predetermined area was measured. The evaluation results are shown as an index with the conventional example being 100, using the reciprocal of the measured value. The larger the index value, the better the driving performance on snow.

As can be seen from Tables 1 and 2, the tires of Examples 1 to 18 and Reference Example 1 were excellent in both on-ice driving performance and on-snow driving performance in comparison with the conventional example.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 11 1st circumferential direction main groove 12 2nd circumferential direction main groove 13 Circumferential direction auxiliary groove 21 1st lug groove 22 2nd lug groove 23 3rd lug groove 30 Center rib 32,42 , 52 Sipe 40 Intermediate block row 41 Intermediate block 41A to 41E First to fifth blocks 50 Shoulder block row 51 Shoulder block

Claims (9)

An annular tread portion extending in the tire circumferential direction, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed on the inner side in the tire radial direction of the sidewall portions. In the provided pneumatic tire,
In the tread portion, a pair of first circumferential main grooves extending in the tire circumferential direction on both sides of the tire equator, and a pair extending along the tire circumferential direction on the outer side in the tire width direction of each first circumferential main groove. A second circumferential main groove, a plurality of first lug grooves extending from the first circumferential main groove toward the grounding end toward the outer side in the tire width direction, and a pair of first lugs adjacent in the tire circumferential direction A second lug groove extending in the tire width direction between the grooves, a third lug groove extending in the tire width direction between the pair of first lug grooves, and a tire circumferential direction between the pair of first lug grooves A circumferential auxiliary groove extending between the pair of first circumferential main grooves, a center rib is defined between the pair of first circumferential main grooves, and between the first circumferential main groove and the second circumferential main groove. The first block facing both the first circumferential main groove and the second circumferential main groove, the first circumferential main groove and the second circumference An intermediate block row constituted as a repeating unit of the second block to a group of intermediate block consisting of a fifth block faces only one of the direction main grooves is partitioned, the tire width direction of the second circumferential main groove defines a shoulder block row composed of a plurality of shoulder blocks on the outside, the center rib, the intermediate block and Rutotomoni a plurality of sipes extending in the tire width direction in each of the shoulder block,
The second lug groove that divides the first block, the second block, and the third block is bent, and the second lug groove has an inclination direction reversed with respect to the tire width direction at the bending point. Pneumatic tire characterized by.   2. The pneumatic tire according to claim 1, wherein a maximum width W <b> 1 of the first block in the tire width direction is 90% to 100% of a total width W <b> 2 of the intermediate block row.   In the group of intermediate blocks, the total surface area S1 of the tread surfaces of the second block and the third block adjacent to the first block and the tread surfaces of the fourth block and the fifth block adjacent to the second block and the third block. 3. The pneumatic tire according to claim 1, wherein the total surface area S <b> 2 has a relationship of S <b> 1> S <b> 2.   4. The pneumatic tire according to claim 3, wherein the total surface area S <b> 1 and the total surface area S <b> 2 have a relationship of 1.2 ≦ S1 / S2 ≦ 1.5. 5.   The maximum width G1 in the intermediate block row of the first lug grooves, and the maximum width in the intermediate block row of the second lug grooves that divide the first block, the second block, and the third block. G2 and the maximum width G3 of the third lug groove that divides the second block, the third block, the fourth block, and the fifth block in the intermediate block row are 1.0 <G1 / The pneumatic tire according to claim 1, wherein G2 ≦ 2.5 and 1.0 <G1 / G3 ≦ 2.5. The pneumatic tire according to any one of claims 1 to 5, wherein the inclination angle θ1 with respect to the tire width direction of both side portions of the bending point of the second lug grooves is 10 ° to 30 °. The pneumatic according to any one of claims 1 to 6, characterized in that the third lug grooves that separate the said second block and the third block and the fourth block and the fifth block is bent tire. The pneumatic tire according to claim 7 , wherein the third lug groove has an inclination direction with respect to the tire width direction reversed at a bending point. The pneumatic tire according to claim 8 , wherein an inclination angle θ <b> 2 with respect to a tire width direction of both side portions of the bending point of the third lug groove is 10 ° to 30 °.

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