JP2009023654A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of enhancing abrasion life while maintaining operation stability in dry and wet to the same level as conventional. <P>SOLUTION: In the pneumatic tire, a tire rotation direction R is designated in one direction. At left and right areas 1A, 1B on both sides of a tread center line CL of a tread surface 1, left and right main inclination grooves 2 extending over a tread ground-contact end E in a curved shape becoming a projection shape in a tire rotation direction at a predetermined curvature while inclined in the tire rotation direction from an origin A on a tread center side toward an outer side in a tread width direction are arranged at the left and right areas 1A, 1B at a predetermined pitch while deviated in the tire circumferential direction TC. On the tire rotation direction R side of the left and right main inclination grooves 2, a sub-inclination groove 3 extending while inclined in the tire rotation direction from a position left from the origin A to an outer side in the tread width direction toward an outer side in the tread width direction is provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic tire having a directional pattern, and more particularly to a pneumatic tire in which wear resistance is improved while maintaining dry performance and wet performance.

  Conventionally, as a pneumatic tire capable of running on public roads mainly for use in competitions, as shown in FIG. 8, when the tire rotation direction is R, it extends while inclining in the tire anti-rotation direction toward the outer side of the tread. A first inclined portion 21, a second inclined portion 22 extending while inclining in the tire rotation direction R from the inner end of the first inclined portion 21 toward the outer side of the tread, and an outer side of the tread from the outer end of the second inclined portion 22 There is a pneumatic tire in which bent grooves 24 having third inclined portions 23 extending while being inclined in the counter-rotating direction of the tire are alternately arranged on the left and right of the tread surface 25 along the tire circumferential direction (for example, Patent Documents). 1).

The pneumatic tire can ensure drainage by the bent grooves 24 and improve the handling stability on the wet road surface. On the other hand, zigzag ribs 26 are formed in the tread center portions by the alternately arranged bent grooves 24. The rib 26 ensures the rigidity in the tire circumferential direction and the oblique direction to improve the steering stability on the dry road surface. However, partial damage and uneven wear occur in the rib portions adjacent to the respective bent portions of the bent groove 24, and the wear grows rapidly and the wear of the rib portion 27 surrounded by the bent groove 24 progresses quickly. There was a problem of being short.
JP 2001-294020 A

An object of the present invention is to provide a pneumatic tire capable of improving the wear life while maintaining the handling stability at the time of dry and wet at the same level as before.

This onset Ming pneumatic tire for achieving the above object is a pneumatic tire which tire rotational direction is specified in one direction, the left and right regions of the tread center line on both sides of the tread surface, the tread center-side origin A The left and right main inclined grooves extending beyond the tread grounding edge in the same region while tilting in a curved shape that protrudes toward the tread center with a predetermined curvature and extending toward the tire counter-rotating direction While shifting in the tire circumferential direction in the region and disposing at a predetermined pitch, the tire counter-rotates from the position spaced from the starting point A to the outer side in the tread width direction toward the outer side in the tread width direction on the tire rotating direction side of the left and right main inclined grooves A sub-inclined groove extending at least to the tread grounding end while being inclined in the direction is arranged.

  According to the present invention described above, the main rib portion extending in a zigzag shape in the tire circumferential direction at the tread center portion and the sub rib portion for supporting the main rib portion from the left and right on the tire counter-rotation direction side by the main inclined groove and the sub inclined groove. Therefore, it is possible to ensure the tread rigidity in the tire circumferential direction and the oblique direction in the same manner as in the prior art, and to maintain the steering stability when dry at the same level as in the prior art.

  In addition, the main slant groove and the sub slant groove that incline in the tire counter-rotation direction toward the outside function to blow off the water on the road surface to the outside in the tread width direction when driving on a wet road surface, so when turning on a wet road surface In addition, it is possible to obtain the same high drainage performance as in the prior art when the vehicle is traveling straight, and thus it is possible to ensure the handling stability during wet operation.

  In addition, the number of corners of the rib portion sandwiched between the main inclined groove and the sub-inclined groove, which is likely to cause partial damage and uneven wear, can be reduced, so that the growth of uneven damage and uneven wear in the rib portion is suppressed. Thus, the progress of wear at the rib portion can be suppressed. Therefore, the wear life can be improved.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, first, a comparative tire similar to the pneumatic tire of the present invention will be described with reference to FIGS. 1 to 5, and then the pneumatic tire of the present invention will be described with reference to FIGS.

FIG. 1 shows a tread pattern of a comparative tire similar to the pneumatic tire of the present invention, in which the tire rotation direction is designated as one direction indicated by an arrow R. The left and right regions 1A and 1B on both sides of the tread center line CL of the tread surface 1 extend from the starting point A on the tread center side in the vicinity of the tread center line CL in the tire anti-rotation direction, and the tire anti-rotation with a predetermined curvature. Left and right main inclined grooves 2 extending beyond the tread ground contact edge E in the same region 1A, 1B while inclining in a curved shape convex toward the direction side (tread center side) have a predetermined pitch in the tire circumferential direction TC. Is arranged in.

  In the illustrated example, each main inclined groove 2 extends while inclining toward the tire counter-rotating direction from the starting point A toward the outer side in the tread width direction, and gradually treads away from the tread center line CL while being tread with a predetermined curvature. It extends beyond the ground contact E to the tread end 1X. The left and right main inclined grooves 2 are alternately arranged in the tire circumferential direction TC while being shifted by a half pitch in the tire circumferential direction TC in the left and right regions 1A and 1B.

  On the tire rotation direction R side of each of the left and right main inclined grooves 2, sub-inclined grooves 3 extending while inclining in the tire counter-rotating direction from the starting point A toward the outer side in the tread width direction are arranged. Each sub-inclined groove 3 extends from the tread ground end E to a position on the inner side in the tread width direction, and does not communicate with the tread ground end E.

  On the tread surface 1, the main inclined groove 2 and the auxiliary inclined groove 3, one main rib portion 4 extending in a zigzag shape indicated by a two-dot chain line in the tire circumferential direction TC at the tread center portion, and the main rib portion A rib 7 is formed which extends from 4 to the left and right in a direction opposite to the tire counter-rotation direction, and includes sub-rib portions 5 that support the main rib portion 4 from the tire counter-rotation direction.

  The sub-inclined groove 3 is formed in a curved shape made of a convex arc on the tire rotation direction R side (tread width direction outer side) with a predetermined curvature in FIG. 1, but as shown in FIG. Thus, it may be formed in a curved line consisting of a convex arc on the tire counter-rotation direction side (tread center side), or may be formed in a straight line as shown in FIG. Preferably, in order to increase the rigidity of the rib portion 6 sandwiched between the main inclined groove 2 and the sub-inclined groove 3 to further suppress damage and wear of the rib portion 6, the structure shown in FIG.

  The main inclined groove 2 may have a shape as shown in FIGS. That is, after extending from the starting point A toward the inner side in the tread width direction (tread center side) with a predetermined curvature while greatly tilting in the tire counter-rotation direction side (not reaching the tread center line CL), the tread It extends in a curved shape with a predetermined curvature over the tread ground end E to the tread end 1X while inclining in the tire counter-rotation direction side toward the outer side in the width direction. The groove 2n from the tread grounding end E to the tread end 1X has a groove width narrower than that of the main body. The main inclined groove 2 of FIGS. 4 and 5 has a starting point A that is separated from the tread center line CL from the main inclined groove 2 shown in FIG. 1, thereby increasing the rigidity of the main rib portion 4, and steering stability during dry operation. Is increasing.

  As shown in FIGS. 3 and 5, the intersection of the main inclined groove 2 and the tread grounding end E is B, and the straight line S′2 passing through the starting point A and the outer end 3x of the auxiliary inclined groove 3 and the tread grounding end E are Assuming that the intersection point is D ′, the inclination angle α1 of the straight line S1 connecting the starting point A and the intersection point B in the same main inclined groove 2 with respect to the tire circumferential direction TC, and the inclination angle α′2 of the straight line S′2 with respect to the tire circumferential direction TC Is α′2> α1.

  The main inclined groove 2 and the sub inclined groove 3 have a groove width of 9.0 mm to 13.0 mm, a groove depth of 5 mm to 6.5 mm, a groove area ratio of the tread surface 1 of 25% to 30%, and a main inclined groove 2. As the number of pitches when one is arranged over a circumference at a predetermined pitch, it can be in the range of 14 to 18 pitches.

  According to the pneumatic tire described above, the main inclined groove 2 and the auxiliary inclined groove 3 allow the main rib portion 4 extending in a zigzag manner in the tire circumferential direction TC to the tread center portion and the main rib portion 4 on the tire anti-rotation direction side. Since the auxiliary rib portions 5 supported from the left and right are formed, it is possible to secure the same tread rigidity in the tire circumferential direction and the diagonal direction as in the conventional case, and to obtain the same level of driving stability on the dry road surface as in the conventional case.

  Further, the main inclined groove 2 and the auxiliary inclined groove 3 which are inclined in the tire counter-rotating direction toward the outside function to blow off water on the road surface outward in the tread width direction during traveling. Since the high drainage performance can be exhibited at the time or when going straight ahead, it is possible to ensure the handling stability at the same level of wetness as in the prior art.

  In addition, since the corner portion 6a of the rib portion 6 sandwiched between the main inclined groove 2 and the sub inclined groove 3 is likely to be partially damaged or unevenly worn, the number of the corner portions 6a can be reduced as compared with the prior art. Further, the growth of damage and uneven wear can be suppressed, the progress of wear of the rib portion 6 can be suppressed, and the wear life can be extended.

  In the pneumatic tire described above, as shown in FIGS. 3 and 5, the distance from the tread center to the starting point A (the distance measured in parallel with the tire axis) WA is 25% or less of the half width W of the tread ground contact width (0 ~ 25%). If the distance WA exceeds 25% of the half width W of the tread contact width, it is difficult to ensure drainage. Preferably, the distance WA is 10 to 20%.

  The tire circumferential length LAB from the starting point A to the intersection point B is preferably 1.20 W to 1.60 W with respect to the half width W of the tread contact width. When the tire circumferential direction length LAB is shorter than 1.20 W, drainage performance particularly when traveling straight is deteriorated. Conversely, if the tire circumferential length LAB is longer than 1.60 W, the groove portion of the main inclined groove 2 near the tread center is longer in the tire circumferential direction when the radius of curvature of the main inclined groove 2 is set to a preferable range. As a result, in the rib portion on the tread center side adjacent to the groove portion, the rigidity is lowered and the rib portion is easily deformed during cornering, so that wear (damage) is likely to occur. In addition, steering stability is reduced. Preferably, the tire circumferential length LAB is set to 1.30 W to 1.40 W.

  In the main inclined groove 2, the tire circumferential length LAC between the starting point A and the position C where the half width W of the tread contact width is W / 2 from the tread center is 0.90 W with respect to the half width W of the tread contact width. It should be in the range of ~ 1.20W. When the tire circumferential length LAC is less than 0.90 W, the rigidity of the rib portion 6 on the tread center side is lowered, and wear (damage) is likely to occur. Moreover, the drainage property at the time of going straight becomes easy to fall. On the contrary, if the tire circumferential length LAC exceeds 1.20 W, the groove portion of the main inclined groove 2 near the tread center becomes longer in the tire circumferential direction when the radius of curvature of the main inclined groove 2 is set to a preferable range. As a result, in the rib portion on the tread center side adjacent to the groove portion, the rigidity is lowered and the rib portion is easily deformed during cornering, so that wear (damage) is likely to occur. In addition, steering stability is reduced. Preferably, the tire circumferential length LAC is 1.00 to 1.10 W.

  If the length in the tire circumferential direction between the intersections B and B between the two main inclined grooves 2 and 2 adjacent to both sides in the tire circumferential direction of the sub-inclined groove 3 is LBB, the tire rotational direction R side The length LBD ′ in the tire circumferential direction from the intersection point B to the intersection point D ′ of the one main inclined groove 2M that is positioned is preferably in the range of 0.45 LBB to 0.85 LBB. If the tire circumferential length LBD ′ is less than 0.45 LBB, the sub-inclined groove 3 is close to the adjacent main inclined groove 2, so that the rib portion between the sub-inclined groove 3 and the adjacent main inclined groove 2 The rigidity is lowered, which tends to cause uneven wear and lower steering stability. On the contrary, when the tire circumferential length LBD ′ exceeds 0.85 LBB, the rigidity of the rib portion 6 sandwiched between the main inclined groove 2 and the sub inclined groove 3 is lowered, thereby causing uneven wear and steering stability. It tends to cause a decrease. Preferably, the tire circumferential length LBD ′ is set to 0.5 LBB to 0.6 LBB.

As shown in FIGS. 1 to 3, when the main inclined groove 2 extends while inclining in the tire counter-rotation direction side directly from the starting point A toward the outer side in the tread width direction, one arc having a curvature radius of 120 mm or more, or the curvature A plurality of arcs having a radius of 120 mm or more are preferably connected to each other. If it comprises from a circular arc with a curvature radius less than 120 mm, it will become easy to generate | occur | produce a damage and partial wear in the rib part adjacent to the main inclined groove 2 at the time of cornering. The maximum value of the radius of curvature is preferably 300 mm or less from the viewpoint of steering stability and wear resistance. Preferably, the radius of curvature is 160 to 240 mm.

  As shown in FIGS. 4 and 5, when the main inclined groove 2 extends from the starting point A toward the tire counter-rotation direction side and extends toward the tread width direction inside and then extends toward the tread width direction outside. The main inclined groove 2 is preferably formed in a curved shape combining a plurality of arcs. As a combination thereof, a groove portion extending inward in the tread width direction of the main inclined groove 2 (after extending inward in the tread width direction from the starting point A to the outer side of the tread width direction, the tread center line CL from the same tread width direction position as the starting point A) 2A is formed in an arc shape having a radius of curvature of 60 mm or more, and the groove portion 2B extending from the groove portion 2A to the outer side in the tire width direction is formed by at least one arc having a radius of curvature of 120 mm or more. It is good to form in the shape.

  The reason why the radius of curvature of the groove 2A is set to 60 mm or more is to improve steering stability and wet performance (drainage performance) during drying while suppressing wear (damage) during cornering. The reason why the radius of curvature of the groove 2B is 120 mm or more is the same as the case where the radius of curvature of the main inclined groove 2 is 120 mm. The upper limit value of the radius of curvature of the groove 2A is preferably 120 mm or less from the viewpoint of handling stability during drying and wet performance (drainage). As with the main inclined groove 2 shown in FIGS. 1 to 3, the upper limit value and the preferred range of the radius of curvature of the groove 2B can be set to 300 mm or less, and the preferred radius of curvature is set to 160 to 240 mm.

  In the example shown in FIGS. 4 and 5, the groove 2B is formed in an arc shape combining two arcs, and a total of three arcs are combined. When the radius of curvature of the arc of the groove 2A is R1, the radius of curvature of the arc of the portion 2Ba of the groove 2B following the groove 2A is R2, and the radius of curvature of the arc of the portion 2Bb following the portion 2Ba is R3, the relationship of R1 <R2 <R3 It has become.

6 and 7, a pneumatic tire of the present invention than the comparative tires described above was to further improve the wear life, each represent an embodiment, the tread width direction outer sub oblique grooves 3 as described above from a starting point A It extends at least to the tread ground contact E while inclining in the tire counter-rotating direction toward the outer side in the tread width direction from the position separated from the tread. The sub-inclined groove 3 of the pneumatic tire in FIG. 6 is formed in a curved shape made of a convex arc on the tire counter-rotating direction side with a predetermined curvature, and the sub-inclined groove 3 of the pneumatic tire in FIG. Although extending in a straight line, as shown in FIG. 1, it may be formed in a curved line formed by a convex arc on the tire rotation direction R side with a predetermined curvature.

  Each sub-inclined groove 3 is not in communication with the main inclined groove 2, but as shown in FIG. 7, the virtual extension 3 y extending toward the tread center along the extending direction intersects the starting point A. Has been placed. Assuming that the intersection of the sub-inclined groove 3 and the tread ground contact E is D, the inclination angle α1, the starting point A and the starting point A of the straight line S1 connecting the starting point A and the intersecting point B of the same main inclined groove 2 are The relation between the inclination angle α2 of the straight line S2 connecting the intersections D of the sub-inclined grooves 3 adjacent to the tire rotating direction R side of the main inclined groove 2 is α2> α1.

  Other configurations are the same as those of the above-described embodiment, and the same components are denoted by the same reference numerals and detailed description thereof is omitted. Even if such a directional pattern is formed on the tread surface 1, the wear life can be improved while maintaining the steering stability at the time of dry and wet at the same level as in the conventional case.

  The tire circumferential length LBD from the intersection B of one main inclined groove 2M located on the tire rotation direction R side to the intersection D of the auxiliary inclined groove 3 can be made the same as the tire circumferential length LBD ′. . Further, the distance from the tread center to the starting point A (a distance measured in parallel to the tire axis) WA, the tire circumferential length LAB from the starting point A to the intersection B, and the half width W of the tread center to tread contact width in the main inclined groove 2 The length LAC in the tire circumferential direction between the position C and the starting point A at W / 2 can be the same as described above.

  In the present invention, the starting point A, the intersection point B, the position C, and the intersection point D are positions on the center line of the inclined grooves 2 and 3. The tread ground width is a ground width defined as 75% of the JATMA design cross-sectional width, and the tread ground end E is a ground end at the ground width, and the JATMA design cross-section from the tread center to the outside in the tread width direction. The position is 1/2 of 75% of the width.

  The straight line S′2 passing through the starting point A and the outer end 3x of the auxiliary inclined groove 3 is defined as follows. That is, in the outer end 3x of the sub-inclined groove 3 extending with the same groove width GW, as shown in FIG. 3, when the groove width GW does not decrease, the end x of the outer end 3x on the groove center line and A straight line passing through the starting point A. When the groove width GW decreases at the outer end 3x as shown in FIGS. 1, 2, 4 and 5, it is a straight line passing through the position P (on the groove center) where the decrease starts and the starting point A.

  The present invention is a public road run mainly intended for use in competitions, in which the groove depth of the main inclined groove 2 and the auxiliary inclined groove 3 is 6 mm or less (5 mm to 6 mm) and the groove area ratio is 25% to 30%. Although it can use preferably for the possible pneumatic tire, it is not limited to it, The other pneumatic tire for passenger cars etc. may be sufficient.

Comparative tire 1 ( comparative example 1) having the tread pattern shown in FIG. 1, tire of the present invention 1 having the tread pattern shown in FIG. 6 (Example 1 ), shown in FIG. Comparative tire 2 having a tread pattern (Comparative example 2), and were produced as test tires a conventional tire (conventional example) having a tread pattern that a bending groove is arranged as shown in FIG.

In the tire 1 of the present invention and the comparative tire 1 , the main inclined groove is formed in a curved shape consisting of one arc having a radius of curvature of 160 mm, the distance WA is 14% of the half width W of the tread contact width, and the tire circumferential length LAB is The tire circumferential direction length LAC is 1.4 W. Further, the tire circumferential direction length LBD ′ of the comparative tire 1 is 0.80 LBB, and the tire circumferential direction length LBD of the tire 1 of the present invention is 0.50 LBB.

In the comparative tire 2 , the main inclined groove is formed in a curved shape formed by combining three arcs having curvature radii of 80 (R1) mm, 120 (R2) mm, and 200 (R3) mm, and the distance WA is a half width of the tread contact width. 14% of W, tire circumferential length LAB is 1.4 W, tire circumferential length LAC is 1.08 W, and tire circumferential length LBD ′ is 0.67 LBB.

In the tire 1 of the present invention and the comparative tires 1 and 2 , the main inclined groove and the auxiliary inclined groove have a groove width of 11 mm, a groove depth of 5 mm, and a groove area ratio of 25%.

  Each of these test tires is mounted on a rim having a rim size of 17 × 9 JJ, mounted on a four-wheel drive vehicle (one-seater) with a displacement of 2000 cc, the tire air pressure after form-up is 220 kPa, and the following test method is used: The results shown in Table 1 were obtained when an evaluation test was performed on the handling stability and running time during dry and wet, tread pattern damage, and wear life.

Steering stability when dry A feeling test by a test driver was performed on a dry road circuit course, and the evaluation result was shown as an index with the conventional tire as 100. The larger the index value, the better the steering stability.

Driving time when dry The time required for the section driving specified during the driving stability evaluation test was measured, and the result was shown as an index with the conventional tire as 100. A larger index value indicates a shorter travel time.

Steering stability when wet A test test by a test driver was conducted on a wet road test course, and the evaluation result was shown as an index with the conventional tire as 100. The larger the index value, the better the steering stability.

Running time when wet We measured the time required for running in the specified section during the evaluation test of steering stability when wet, and showed the result as an index with the conventional tire as 100. A larger index value indicates a shorter travel time.

Tread pattern damage After evaluating the steering stability during the above dry operation, the center part of the tread surface where the main rib part extends, the rib part adjacent to the main inclined groove (side part of the main inclined groove), the main inclined groove and the auxiliary The rib damage between the inclined grooves and the shoulder portion were evaluated for five levels of damage to the ribs. A larger evaluation score means less damage.

Abrasion life After evaluating the steering stability at the time of drying, the wear amount of the tread surface was measured, and the evaluation result was shown as an index with the conventional tire as 100. The larger the index value, the better the wear life.

  From Table 1, it can be seen that the tire of the present invention can improve the wear life while maintaining the handling stability at the time of dry and wet at the same level or higher.

FIG. 3 is a partial development view of a tread surface showing a comparative tire described in comparison with the pneumatic tire of the present invention. It is a partial expanded view of the tread surface which shows the other aspect of a comparative tire . It is a principal part enlarged view of the tread surface which shows the other aspect of a comparative tire . It is a principal part enlarged view of the tread surface which shows the other aspect of a comparative tire . It is the elements on larger scale of FIG. It is a partial development view of a tread surface showing an embodiment of a pneumatic tire of the present invention. It is an enlarged view of a tread surface showing another embodiment of the pneumatic tire of the present invention. It is a partial expanded view of the tread surface of the conventional tire.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tread surface 1A, 1B Area | region 2, 2M Main inclination groove 3 Sub inclination groove 3x, 3y Virtual extension part 4 Main rib part 5 Sub rib part 6 Rib part CL Tread centerline E Tread contact edge R Tire rotation direction TC Tire circumferential direction

Claims (11)

  A pneumatic tire in which the tire rotation direction is designated as one direction, and extends in the left and right regions on both sides of the tread center line of the tread surface from the starting point A on the tread center side toward the tire counter-rotation direction and a predetermined direction. The left and right main inclined grooves extending beyond the tread ground contact edge in the same region while being inclined in a curved shape convex toward the tread center due to the curvature are shifted in the tire circumferential direction in the left and right regions and arranged at a predetermined pitch. On the other hand, the left and right main inclined grooves extend to at least the tread ground contact end while being inclined in the tire counter-rotating direction from the position spaced from the starting point A to the tread width direction outer side toward the tire tread width direction outer side. Pneumatic tire with inclined grooves. 2. The pneumatic tire according to claim 1 , wherein the secondary inclined groove is disposed so that a virtual extension extending to the tread center side along the direction in which the secondary inclined groove extends intersects the starting point A. 3. The intersection of the sub-inclined groove and the tread grounding end is D, and the tire circumferential length between the intersections B and B of the two main inclined grooves and the tread grounding end adjacent to both sides of the sub-inclined groove in the tire circumferential direction is LBB. When pneumatic tire according to claim 2 tire circumferential direction length LBD from the intersection B of the main slant grooves located in the tire rotation direction side to the intersection D is 0.45LBB～0.85LBB. An inclination angle α1 with respect to the tire circumferential direction of a straight line connecting the starting point A and the intersection point B of the same main inclined groove, and an intersection D of the auxiliary inclined groove adjacent to the starting point A and the main inclined groove having the starting point A on the tire rotation direction side. The pneumatic tire according to claim 3 , wherein a relationship between the connecting straight line and the inclination angle α2 with respect to the tire circumferential direction is α2> α1. The pneumatic tire according to any one of claims 1 to 4 , wherein a distance WA from the tread center to the starting point A is 25% or less of a half width W of the tread contact width. Tire circumferential direction length LAB from the origin A to the intersection B of the main oblique groove and a tread ground end, any one of claims 1 to 5 is 1.20W~1.60W relative half width W of the tread width Pneumatic tire described in 2. In the main inclined groove, the length LAC in the tire circumferential direction between the position C where the half width W of the tread contact width is W / 2 from the tread center and the starting point A is 0.90 W to the half width W of the tread contact width. The pneumatic tire according to claim 6 which is 1.20W. The pneumatic tire according to any one of claims 1 to 7 , wherein each main inclined groove extends from the starting point A toward the outer side in the tread width direction while being inclined toward the tire counter-rotating direction. The pneumatic tire according to claim 8 , wherein the main inclined groove is formed in a curved shape including at least one arc having a curvature radius of 120 mm or more. Each main oblique grooves are, while inclined from the origin A of the tire reverse rotation direction side, according to any one of claims 1 to 7 extends toward the tread width direction outer after extending inward tread width direction Pneumatic tires. The main inclined groove is formed in a curved shape combining a plurality of arcs, and a groove portion extending inward in the tread width direction of the main inclined groove is formed in an arc shape having a radius of curvature of 60 mm or more. The pneumatic tire according to claim 10 , wherein the groove portion extending in the shape of a curved line is formed of at least one arc having a curvature radius of 120 mm or more.

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