JP2015131619A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve on-snow performance.SOLUTION: A tire 10 (one example of pneumatic tires) whose rotating direction is specified has: main grooves 14 that are provided in a plural number at intervals in a tread 12 in a tire circumference direction and extended to a tread end 12E so that an angle θ1 relative to a tire width direction becomes gradually smaller from an inner end portion 14A positioned at a tread center portion 12C toward the opposite direction of the tire rotating direction; first sub grooves 16 that are extended in a normal direction of the main grooves 14 from the main grooves 14 toward the tire rotating direction and terminated without reaching the main grooves 14 adjacent in the tire rotating direction; and second sub grooves 18 that are provided closer to a tire equator CL than the first sub grooves 16, extended in a normal direction of the main grooves 14 from the main grooves 14 toward the tire rotating direction, reach the main grooves 14 adjacent in the tire rotating direction and have the first sub grooves 16, extended from the main grooves adjacent in the tire rotating direction, arranged in an extension line.

Description

  The present invention relates to a pneumatic tire.

  Among the tires for which the rotation direction is specified, there are a plurality of inclined grooves that extend while curving from the end on the tire equator side opposite to the tire rotation direction and outward in the tire width direction, and along the tire circumferential direction. A main groove that connects the ends of the inclined grooves adjacent to each other in the tire circumferential direction on the tire equator side, and an inclined auxiliary groove that extends from the inclined groove toward the tire rotation direction and toward the tire equator side. There is a formed tire (for example, Patent Document 1).

JP 2012-236536 A

  In the above-mentioned tire, wet performance and on-snow performance can be secured by the inclined groove and the inclined sub-groove, but there is still room for improvement on the on-snow performance.

  An object of the present invention is to improve the performance on snow.

  The pneumatic tire according to claim 1 of the present invention is a pneumatic tire in which a rotation direction is specified, and a plurality of inner tires are provided in the tread at intervals in the tire circumferential direction and located at the tread center portion. A main groove extending to the tread end so that an angle with respect to the tire width direction gradually decreases from the tire rotation direction to the tire rotation direction, and is provided in the tread, from the main groove to the tire rotation direction side in the normal direction of the main groove A first sub-groove that extends and terminates without reaching the main groove adjacent to the tire rotation direction, and is provided closer to the tire equator than the first sub-groove of the tread, and from the main groove to the tire rotation direction side A second sub-groove that extends in the normal direction of the main groove, reaches the main groove adjacent to the tire rotation direction, and the first sub-groove extends from the main groove adjacent to the tire rotation direction on the extension line. And have .

  In the pneumatic tire according to claim 1, the main groove extends from the inner end portion located in the tread center portion to the tread end so that the angle with respect to the tire width direction gradually decreases from the tire rotation direction to the opposite side. A long snow column can be formed by the main groove when traveling on the road on snow. As a result, the shear force of the snow column (hereinafter referred to as “snow column shear force” as appropriate) is improved, and the performance on snow (acceleration performance on snow and braking performance on snow) of the tire using the snow column shear force is improved. .

Further, in the pneumatic tire, the first sub-groove extends from the main groove to the tire rotation direction side in the normal direction of the main groove and is terminated without reaching the main groove adjacent to the tire rotation direction. Since snow can be retained in the first sub-groove during braking, the on-snow braking performance is improved by the shear force of the snow column formed by the first sub-groove.
Here, the “normal direction of the main groove” includes a direction along the normal line of the groove center line of the main groove and a direction inclined within a range of ± 10 degrees with respect to the normal line.

  Further, in the pneumatic tire, the second sub-groove extends from the main groove to the tire rotation direction side in the normal direction of the main groove and reaches the main groove adjacent to the tire rotation direction. Two joining portions with the main groove are formed. In these merged portions, a snow column straddling the main groove and the second sub-groove is formed when traveling on the snow road surface, so that the performance on snow using the snow column shearing force is improved. Further, since the first sub-groove of the main groove adjacent to the tire rotation direction is arranged on the extended line of the second sub-groove extending from the main groove, the second sub-groove extending from the main groove is adjacent to the tire rotation direction. A long snow column can be formed by the first sub-groove extending from the main groove. Thereby, the performance on snow using a snow column shear force further improves.

  Moreover, since the 1st subgroove is extended in the normal line direction of the main groove, the rigidity of the land part corner formed between the main groove and the 1st subgroove is securable. And since the 2nd subgroove is extended along the normal line direction of a main groove, the rigidity of the land part corner formed between a main groove and a 2nd subgroove is securable. Thereby, the ground contact property of the land part formed between the main grooves adjacent to the tire circumferential direction is improved, and the on-snow maneuvering stability is improved.

  From the above, according to the pneumatic tire of the first aspect, the performance on snow (acceleration performance on snow, braking performance on snow, and steering stability on snow) can be improved.

  The pneumatic tire according to claim 2 of the present invention is the pneumatic tire according to claim 1, wherein the first sub-groove extending from the main groove is spaced in the extending direction of the main groove in the tread. A plurality of first sub-grooves extending from the main groove adjacent to the tire rotating direction on the extension line of the second sub-groove extending from the main groove. One sub-groove is arranged.

  In the pneumatic tire according to claim 2, since a plurality of first sub-grooves extending from the main groove are provided in the tread at intervals in the extending direction of the main groove, performance on snow is improved. On the other hand, since the first sub-groove closest to the tire equator is disposed among the plurality of first sub-grooves extending from the main groove adjacent to the tire rotation direction on the extension line of the second sub-groove extending from the main groove, the most tire equator is arranged. Since the size of the land portion formed between the first sub-groove on the side and the second sub-groove can be secured, it is possible to suppress a decrease in rigidity of the land portion.

  The pneumatic tire according to claim 3 of the present invention is the pneumatic tire according to claim 1 or 2, wherein the first sub-groove has a groove depth greater than that of the main groove and the second sub-groove. Also shallow.

  In the pneumatic tire according to claim 3, the groove depth of the first sub-groove is made shallower than the main groove and the second sub-groove, thereby ensuring on-snow acceleration performance and on-snow braking performance by the first sub-groove. In addition, the rigidity of the land portion formed between the main grooves adjacent to each other in the tire circumferential direction can be ensured to ensure snow handling stability.

  The pneumatic tire according to claim 4 of the present invention is the pneumatic tire according to any one of claims 1 to 3, wherein the main grooves are provided on both sides in the tire width direction across the tire equator. In the tread, rib-like land portions that are continuous in the tire circumferential direction are formed between the main groove on both sides in the tire width direction and the second sub-groove on both sides in the tire width direction.

  In the pneumatic tire according to claim 4, the rib-like land portion continuous in the tire circumferential direction is formed between the main groove on both sides in the tire width direction and the second sub-groove on both sides in the tire width direction. Among them, the contact area of the tread center where the contact length becomes the longest increases, and the handling stability on snow improves.

  The pneumatic tire according to claim 5 of the present invention is the pneumatic tire according to claim 4, wherein the main groove on one side in the tire width direction and the main groove on the other side are shifted in the tire circumferential direction. Has been.

  In the pneumatic tire according to claim 5, since the main groove on the one side in the tire width direction and the main groove on the other side are shifted in the tire circumferential direction, the rib-shaped land portion formed in the tread center portion. Since the local narrow portion is not formed, the rigidity of the rib-like land portion can be secured, and the handling stability on snow is improved.

  As described above, the pneumatic tire of the present invention can improve the performance on snow.

It is a tread development view of the pneumatic tire of one embodiment of the present invention. It is an enlarged view of the part (enclosure part) pointed by the arrow 2 of FIG. FIG. 3 is a sectional view taken along line 3-3 in FIG. 2.

  Hereinafter, a pneumatic tire (hereinafter simply referred to as “tire”) 10 according to an embodiment of the present invention will be described. The tire 10 of the present embodiment is a tire whose rotation direction is specified, and is a tire mainly used for passenger cars. In addition, this invention is not limited to this structure, You may use for the pneumatic tire of another use. For example, you may use as pneumatic tires for light trucks, aircrafts, and construction vehicles.

  FIG. 1 is a development view of the tread 12 of the tire 10. An arrow X in FIG. 1 indicates a tire width direction that is a direction parallel to the axis (rotation axis) of the tire 10, and an arrow Y is referred to as a circumferential direction of the tire 10 (hereinafter, “tire circumferential direction” as appropriate). ). Reference sign CL indicates the tire equator, and reference sign R indicates the rotational direction of the tire 10. In the present embodiment, the tire equator CL side along the tire width direction is described as “inner side in the tire width direction”, and the side opposite to the tire equator CL is referred to as “outer side in the tire width direction”.

  Further, reference numeral 12E in FIG. 1 indicates a tread end that is an end portion (end portion in the tire width direction) of the tread width TW of the tread 12.

  The tire 10 of the present embodiment can use the same internal structure as that of a conventionally known pneumatic tire. For this reason, the description of the internal structure of the tire 10 is omitted.

  As shown in FIGS. 1 and 2, a plurality of main grooves 14 are provided in the tread 12 that constitutes a contact portion with the road surface of the tire 10 at intervals in the tire circumferential direction (constant intervals in the present embodiment). ing. The main groove 14 extends from the inner end portion 14A located at the tread center portion 12C to the tread end 12E so that the acute angle angle θ1 with respect to the tire width direction gradually decreases from the tire rotation direction to the opposite side. Specifically, as shown in FIG. 2, a line passing through the center of the groove width of the main groove 14 (hereinafter referred to as “groove center line” as appropriate) 14CL is an angle θ1 from the inner end portion 14A to the tread end 12E. Is curved so as to become gradually smaller.

  In the present embodiment, the tread center portion 12C has a range of 1/2 × TW on both sides in the tire width direction around the tire equator CL. And the tread center part 12C has the tread shoulder part 12S on both sides in the tire width direction.

As shown in FIG. 1, the main groove 14 has an angle with respect to the tire width direction on the inner end portion 14A side of 60 to 90 degrees and an angle with respect to the tire width direction on the tread end 12E side of 0 to 20 degrees. It is preferable to bend. By comprising in this way, the opening edge parts (edge) 14B and 14C of the main groove 14 can exhibit the edge effect of a tire circumferential direction and a tire width direction effectively. The edge 14B of the main groove 14 is an opening edge on the tire rotation direction side, and the edge 14C is an opening edge on the opposite side to the tire rotation direction.
In the present embodiment, the main groove 14 is curved and extended from the inner end portion 14A to the tread end 12E, but the present invention is not limited to this configuration. For example, the main groove 14 may be extended while being bent stepwise from the inner end portion 14A to the tread end 12E.

  The main groove 14 has a groove width wider on the tread end 12E side than on the inner end portion 14A side. Further, in the main groove 14, the radius of curvature of the edge 14B on the tire rotating direction side and the radius of curvature of the edge 14C on the opposite side to the tire rotating direction are substantially the same in the tread shoulder portion 12S. In addition, this invention is not limited to the said structure.

  As shown in FIG. 1, the tread 12 has a first end that extends from the main groove 14 toward the tire rotation direction in the normal direction of the main groove 14 and does not reach the main groove 14 adjacent in the tire rotation direction. A sub-groove 16 is formed. Specifically, the first sub-groove 16 terminates in a rib-like land portion 22 formed between the main grooves 14 adjacent in the tire circumferential direction. The first sub-groove 16 is provided in plural (two in the present embodiment) at intervals in the extending direction of the main groove 14 (the direction along the groove center line 14CL).

  Here, the “normal direction of the main groove 14” refers to a direction along the normal line 14NL of the groove center line 14CL of the main groove 14 and a direction inclined within a range of ± 10 degrees with respect to the normal line 14NL. (See FIG. 2).

  In the present embodiment, as shown in FIG. 2, the groove center line 16CL of the first sub-groove 16 is inclined at an angle θ2 with respect to the normal line 14NL of the main groove 14. The groove center line 16CL of the first sub-groove 16 is a line passing through the center of the groove width of the first sub-groove 16. The angle θ2 is set within a range of −10 degrees to 10 degrees with respect to the normal line 14NL.

  In addition, as shown in FIG. 1, the tread 12 extends along the normal direction of the main groove 14 from the main groove 14 toward the tire rotation direction side toward the tire equator CL side than the first sub-groove 16. A second sub groove 18 reaching the main groove 14 adjacent to the rotation direction is formed. The second sub groove 18 communicates the main grooves 14 adjacent to each other in the tire circumferential direction.

  In the present embodiment, as shown in FIG. 2, the groove center line 18CL of the second sub-groove 18 is inclined at an angle θ3 with respect to the normal line 14NL of the main groove 14. The groove center line 18CL of the second sub groove 18 is a line passing through the center of the groove width of the second sub groove 18. The angle θ3 is set within a range of −10 degrees to 10 degrees with respect to the normal line 14NL, similarly to the angle θ2.

  In the present embodiment, the second sub-groove 18 is disposed in the tread center portion 12C (see FIG. 1). The present invention is not limited to this configuration.

In addition, the second sub-groove 18 has a first sub-groove 16 extending from the main groove 14 adjacent to the tire rotation direction on the extension line. Specifically, on the extension line of the second sub-groove 18, the tire equator CL side of the plurality of (two in the present embodiment) first sub-grooves 16 extending from the main grooves 14 adjacent to each other in the tire rotation direction. The first sub-groove 16 is disposed. The “extension line of the second sub-groove 18” here is a line obtained by extending the groove center line 18CL of the second sub-groove 18. In the present embodiment, the extension line of the second sub-groove 18 and the groove center line 16CL of the first sub-groove 16 closest to the tire equator CL extending from the main groove 14 adjacent in the tire rotation direction coincide with each other.
In addition, this invention is not limited to the said structure, The part of the 1st subgroove 16 extended from the main groove 14 adjacent to the tire rotation direction on the extension line of the 2nd subgroove 18 should just be arrange | positioned. Further, the groove center line 16CL of the first sub-groove 16 extending from the main groove 14 adjacent to the extension line of the second sub-groove 18 in the tire rotation direction may be inclined.

  As shown in FIG. 3, the groove depth D <b> 1 of the first sub-groove 16 is shallower than the groove depth D <b> 0 of the main groove 14 and the groove depth D <b> 2 of the second sub-groove 18. In the present embodiment, the groove depth D0 and the groove depth D1 are set to the same value, but the present invention is not limited to this configuration. For example, the groove depth D1 is shallower than the groove depth D0. May be.

  As shown in FIG. 1, the main groove 14, the first sub-groove 16, and the second sub-groove 18 are respectively provided on both sides in the tire width direction across the tire equator CL. In the present embodiment, the main groove 14 on one side and the main groove 14 on the other side are arranged with a half-pitch shift in the tire circumferential direction with the tire equator CL interposed therebetween. In addition, the half pitch here is a half pitch when the distance between the main grooves 14 adjacent in the tire circumferential direction is 1 pitch.

  Further, in the tread 12 of the present embodiment, only the main groove 14, the first sub-groove 16, and the second sub-groove 18 are formed as grooves that do not close at the time of grounding (grooves in which the groove wall surfaces do not contact each other). In addition, this invention is not limited to the said structure, You may form another groove | channel other than the main groove 14, the 1st subgroove 16, and the 2nd subgroove 18 in the tread 12. FIG.

  Ribbed land portions 20 that are continuous in the tire circumferential direction are formed in the tread 12 between the main grooves 14 on both sides in the tire width direction and the second sub grooves 18 on both sides in the tire width direction. Here, the “rib-like land portion 20 continuous in the tire circumferential direction” includes a state in which the rib-like land portion 20 is continuous in the tire circumferential direction within the contact surface. In the present embodiment, the rib-like land portion 20 extends in a zigzag shape on the tire equator CL in the tire circumferential direction.

  As shown in FIG. 1, a plurality of sipes 30 extending in a direction intersecting the tire circumferential direction (in the present embodiment, the tire width direction) are provided in the rib-like land portion 20 at intervals in the tire circumferential direction. It has been. Here, “sipe” refers to a narrow groove that is set to have a groove width such that the groove wall surfaces come into contact with each other and close at the time of grounding.

  The tread 12 is formed with a rib-like land portion 22 that is continuous in the tire width direction between the main grooves 14 adjacent to each other in the tire circumferential direction and outside the second sub groove 18 in the tire width direction. The rib-like land portion 22 is adjacent to the outer side of the rib-like land portion 20 in the tire width direction.

  As shown in FIG. 1, the rib-like land portion 22 includes a pseudo block portion 22 </ b> A between the second sub groove 18 and the first sub groove 16 closest to the tire equator, and the adjacent first sub groove 16. And a pseudo block portion 22C between the first sub-groove 16 and the tread end 12E. Here, the “pseudo block portion” refers to a portion of a land portion that is not completely divided by a groove but is in a block shape.

  In the block portion 22A, a plurality of sipes 32 extending in a direction intersecting with the tire circumferential direction (in the present embodiment, an oblique direction with respect to the tire circumferential direction) are provided at intervals in the tire circumferential direction.

  The block portion 22B has a sipe 34 extending in the same direction as the sipe 32 in a direction intersecting with the tire circumferential direction (in this embodiment, an oblique direction with respect to the tire circumferential direction). Are provided.

  A plurality of sipes 36 extending in a direction intersecting the tire circumferential direction (in the present embodiment, the tire width direction) are provided in the block portion 22C at intervals in the tire circumferential direction.

Next, the effect of the tire 10 will be described.
In the tire 10, the main groove 14 extends from the inner end portion 14 </ b> A located in the tread center portion 12 </ b> C to the side opposite to the tire rotation direction so that the angle θ <b> 1 with respect to the tire width direction gradually decreases and reaches the tread end 12 </ b> E. Therefore, a long snow column can be formed by the main groove 14 when traveling on a snowy road surface. As a result, the shear force of the snow column (hereinafter referred to as “snow column shear force” as appropriate) is improved, and the performance on the snow (snow acceleration performance and snow braking performance) of the tire 10 using the snow column shear force is improved. To do. Further, when running on a wet road surface, drainage smoothly flows in the main groove 14 from the inner end portion 14A side to the tread end 12E side, so that the drainage performance of the tire 10 is improved. Further, since the groove width of the main groove 14 is wider on the tread end 12E side where the angle with respect to the tire width direction is smaller than that on the inner end portion 14A side, the snow column formed on the tread end 12E side becomes thicker. Acceleration performance and braking performance on snow are improved.

  Further, the main groove 14 extends from the inner end portion 14A to the side opposite to the tire rotation direction so that the angle θ1 with respect to the tire width direction gradually decreases and reaches the tread end 12E. And since the edge 14C exhibits the edge effect in a wide range in the tire circumferential direction and the tire width direction, the performance on snow due to the edge effect is improved. Furthermore, since the flow of the groove in the main groove 14 becomes smooth when traveling on a wet road surface, drainage performance is improved.

  Further, in the tire 10, the first sub-groove 16 extends from the main groove 14 toward the tire rotation direction in the normal direction of the main groove 14, and does not reach the main groove 14 adjacent in the tire rotation direction. Since it is terminated in the snow 22, snow can be retained in the first sub-groove 16 during braking on snow. For this reason, the braking performance on snow is improved by the shear force of the snow column formed by the first sub-groove 16. On the other hand, when accelerating on the snow, the snow in the main groove 14 and the snow in the first sub groove 16 are pressed against each other at the junction of the first sub groove 16 and the main groove 14 to form a strong snow column. The acceleration performance on snow is improved. Further, since the first sub-groove 16 is terminated in the rib-like land portion 22, the edge portion (edge 14C of the main groove 14) on the tire rotation direction side (stepping side) of the rib-like land portion 22 is the first sub-groove. Since it continues for a long time without being divided in the middle by 16, the edge effect at the time of running on a snowy road surface is improved, and the snow acceleration performance is improved. Furthermore, since the first sub groove 16 extends in the normal direction of the main groove 14, the block portion 22 </ b> A, the block portion 22 </ b> B, and the block portion 22 </ b> C formed between the main groove 14 and the first sub groove 16. The rigidity of each corner of the can be secured. Thereby, the ground contact property of the block portions 22A to 22C of the rib-like land portion 22 is improved, and the handling stability on snow is improved. Further, by extending the first sub-groove 16 in the normal direction of the main groove 14, it is possible to suppress the disturbance of the drainage flowing through the main groove 14.

  Further, in the tire 10, the second secondary groove 18 extends from the main groove 14 toward the tire rotation direction in the normal direction of the main groove 14 to reach the main groove 14 adjacent in the tire rotation direction. Two joining portions of the groove 18 and the main groove 14 are formed. In these joining portions, a snow column straddling the main groove 14 and the second sub-groove 18 is formed when traveling on a snowy road surface, so that the performance on snow utilizing the snow column shearing force is improved. In addition, since the first sub-groove 16 of the main groove 14 adjacent to the tire rotation direction is disposed on the extended line of the second sub-groove 18 extending from the main groove 14, the second sub-groove 18 extending from the main groove 14 and A long snow column can be formed by the first sub-groove 16 extending from the main groove 14 adjacent in the tire rotation direction. Thereby, the performance on snow using a snow column shear force further improves. Furthermore, when accelerating on the snow, the snow in the main groove 14 and the snow in the second sub-groove 18 are pressed against each other at the junction of the second sub-groove 18 and the main groove 14 to form a strong snow column. , Acceleration performance on snow is improved. And since the 2nd subgroove 18 is extended along the normal line direction of the main groove 14, the rigidity of the corner | angular part of the block part 22A formed between the main groove 14 and the 2nd subgroove 18 is securable. . Thereby, the ground contact property of the block portion 22A of the rib-like land portion 22 formed between the main grooves 14 adjacent to each other in the tire circumferential direction is improved, and the handling stability on snow is improved. Furthermore, by extending the second sub-groove 18 in the normal direction of the main groove 14, it is possible to suppress turbulence of drainage flowing through the main groove 14.

  In the tire 10, since a plurality of first sub grooves 16 extending from the main groove 14 are provided in the tread 12 at intervals in the extending direction of the main groove 14, the performance on snow is improved. On the other hand, the first sub-groove 16 closest to the tire equator CL among the plurality of first sub-grooves 16 extending from the main groove 14 adjacent in the tire rotation direction is disposed on the extension line of the second sub-groove 18 extending from the main groove 14. Therefore, since the size of the block portion 22A formed between the first sub groove 16 and the second sub groove 18 closest to the tire equator CL can be secured, the rigidity of the block portion 22A of the rib-like land portion 22 is reduced. Can be suppressed.

  In the tire 10, by making the groove depth D1 of the first sub-groove 16 shallower than the groove depth D0 of the main groove and the groove depth D2 of the second sub-groove 18, on-snow acceleration performance by the first sub-groove 16 and While ensuring the braking performance on snow, the rigidity of the block portions 22A, 22B, 22C of the rib-like land portion 22 can be ensured to ensure the stability on snow handling.

  In the tire 10, the sipe 30 is provided in the rib-shaped land portion 20, and the sipe 32, sipe 34, and sipe 36 are provided in the rib-shaped land portion 22. Performance is improved.

  Further, in the tire 10, the tread center portion 12 </ b> C, in particular, the rib-like land portion 20 continuous in the tire circumferential direction is formed on the tire equator CL, and therefore the tread center portion 12 </ b> C having the longest contact length in the tread 12. The ground contact area is increased and the handling stability on snow is improved. Further, by providing the sipe 30 on the rib-like land portion 20, a high edge effect can be obtained.

  Further, in the tire 10, since the main groove 14 on one side and the main groove 14 on the other side in the tire width direction are arranged so as to be shifted in the tire circumferential direction, a local narrow portion is formed in the rib-like land portion 20. It is not formed, and the rigidity of the rib-like land portion 20 can be ensured. Thereby, the ground contact property of the rib-like land portion 20 is improved, and the handling stability on snow is improved. In particular, in the present embodiment, since the inner end portion 14A of the main groove 14 on one side in the tire width direction and the inner end portion 14A of the main groove 14 on the other side are shifted by a half pitch in the tire circumferential direction, the tire equator Edge effects due to the main grooves 14 on both sides of the CL can be generated in a balanced manner.

  From the above, according to the tire 10, the performance on snow (snow acceleration performance, snow braking performance, and snow handling stability) can be improved.

  In the above-described embodiment, as shown in FIG. 1, the inner end 14 </ b> A of the main groove 14 does not cross the tire equator CL, but the present invention is not limited to this configuration, and the inner end of the main groove 14. 14A may cross the tire equator CL. With this configuration, the drainage performance of the main groove 14 is further improved.

  The embodiments of the present invention have been described above with reference to the embodiments. However, these embodiments are merely examples, and various modifications can be made without departing from the scope of the invention. It goes without saying that the scope of rights of the present invention is not limited to these embodiments.

10 Tire (Pneumatic tire)
12 tread 12C tread center portion 12E tread end 14 main groove 14A inner end portion 16 first sub groove 18 second sub groove 20 rib-like land portion CL tire equator X tire width direction Y tire circumferential direction R tire rotation direction

Claims (5)

A plurality of treads provided at intervals in the tire circumferential direction, a main groove extending from the inner end located in the tread center portion to the tread end so that the angle with respect to the tire width direction gradually decreases from the tire rotation direction to the opposite side;
A first sub-groove provided in the tread and extending from the main groove toward the tire rotation direction side in the normal direction of the main groove and ending without reaching the main groove adjacent to the tire rotation direction;
Provided on the tire equator side from the first sub-groove of the tread, extends in the normal direction of the main groove from the main groove toward the tire rotation direction, reaches the main groove adjacent to the tire rotation direction, and extends A second sub-groove in which the first sub-groove extending from the main groove adjacent to the tire rotating direction on the line is disposed;
A pneumatic tire having a specified rotational direction. The tread is provided with a plurality of the first sub-grooves extending from the main groove at intervals in the extending direction of the main groove,
The first sub-groove closest to the tire equator among the plurality of first sub-grooves extending from the main groove adjacent to the tire rotation direction is disposed on an extension line of the second sub-groove extending from the main groove. The pneumatic tire according to claim 1.   The pneumatic tire according to claim 1 or 2, wherein the first sub-groove has a groove depth shallower than that of the main groove and the second sub-groove. The main grooves are respectively provided on both sides of the tire width direction across the tire equator,
The said tread is formed with the rib-like land part which continues in a tire circumferential direction between the said main groove of a tire width direction both sides, and the said 2nd subgroove of both sides of a tire width direction. A pneumatic tire given in any 1 paragraph.   The pneumatic tire according to claim 4, wherein the main groove on one side in the tire width direction and the main groove on the other side are arranged so as to be shifted in the tire circumferential direction.

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