Pneumatic tire
A ratio between the total width (SW) and outer diameter (OD) of a pneumatic tire, which has an asymmetrical pattern formed by grooves formed on a tread part, satisfies SW/OD≤0.3. Given a ground contact width (CW) in a ground contact region in the tread part, a groove area ratio (GR), and a groove area ratio (GRi) of a tire inner side region (Ai), which spans from a tire equator line (CL) to the vehicle side in the ground contact region, and a groove area ratio (GRo) of a tire outer side region (Ao), which spans from the tire equator line to the opposite side of the vehicle side in the ground contact region, the ground contact region is formed to satisfy 0.75≤CW/SW≤0.9, 10≤GR≤25%, and GRi<GRo.
1. A pneumatic tire having an asymmetrical pattern formed by grooves formed on a tread part, wherein
the grooves comprise two circumferential main grooves and two circumferential thin grooves that have groove widths thinner than those of the two circumferential main grooves, wherein the two circumferential main grooves are the only circumferential main grooves of the asymmetrical pattern,
a land portion formed between the two circumferential main grooves includes a tire equator line and no grooves or notches,
a ratio between a total width SW and an outer diameter OD of the pneumatic tire satisfies a relationship
SW/OD≤0.3, and
when a ground contact width in a ground contact region in the tread part is set as CW and a groove area ratio is set as GR, a range, when the pneumatic tire is mounted on a vehicle, positioned from the tire equator line to a vehicle side in the ground contact region is set as a tire inner side region Ai and a groove area ratio in the tire inner side region Ai is set as GRi, and a range, when the pneumatic tire is mounted on a vehicle, positioned from the tire equator line to the opposite side to the vehicle side in the ground contact region is set as a tire outer side region Ao and a groove area ratio in the tire outer side region Ao is set as GRo, the ground contact region is formed so as to satisfy relationships
0.82≤CW/SW≤0.9,
10%≤GR≤25%, and
GRi<GRo.
2. The pneumatic tire according to claim 1 , wherein GR, GRi, and GRo satisfy a relationship
0.1≤(GRo-GRi)/GR≤0.6.
3. The pneumatic tire according to claim 1 , wherein, when a range in the tire inner side region Ai having a width corresponding to 25% of the ground contact width CW positioned on a tire equator line side is set as an inner-outer side region Aio and a groove area ratio in the inner-outer side region Aio is set as GRio, and, when a range in the tire outer side region Ao having a width corresponding to 25% of the ground contact width CW positioned on the tire equator line side is set as an outer-inner side region Aoi and a groove area ratio in the outer-inner side region Aoi is set as GRoi,
GRoi>GRio
is satisfied.
4. The pneumatic tire according to claim 1 , wherein, when a range in the tire outer side region Ao having a width corresponding to 25% of the ground contact width CW positioned on a tire equator line side is set as an outer-inner side region Aoi and a groove area ratio in the outer-inner side region Aoi is set as GRoi, and, when a range in the tire outer side region Ao having a width corresponding to 25% of the ground contact width CW positioned on a tire width direction ground contact edge side is set as a tire outer-outer side region Aoo and a groove area ratio in the outer-outer side region Aoo is set as GRoo, a relationship
GRoi>GRoo
is satisfied.
5. The pneumatic tire according to claim 1 , wherein the two circumferential main grooves are provided in a center region Ac centering on the tire equator line and having a width of 40% of the ground contact width CW.
6. The pneumatic tire according to claim 1 , wherein
width direction grooves extending in a direction crossing the tire equator line are provided in the tread part, and
the width direction grooves are inclined relative to a tire width direction.
7. The pneumatic tire according to claim 6 , wherein
the width direction grooves include a width direction groove provided in the tire outer side region Ao and a width direction groove provided in the tire inner side region Ai; and
an angle of inclination of the width direction groove provided in the tire outer side region Ao is greater than an angle of inclination of the width direction groove provided in the tire inner side region Ai.
8. The pneumatic tire according to claim 1 , wherein, in the tire inner side region Ai and the tire outer side region Ao, the two circumferential thin grooves are provided in shoulder regions As each having a width of 15% of the ground contact width CW from a ground contact edge to the tire equator line in a tire width direction.
9. The pneumatic tire according to claim 1 , wherein sipes extending in a direction crossing the tire equator line are provided in the tire inner side region Ai.
10. The pneumatic tire according to claim 2 , wherein, when a range in the tire inner side region Ai having a width corresponding to 25% of the ground contact width CW positioned on a tire equator line side is set as an inner-outer side region Aio and a groove area ratio in the inner-outer side region Aio is set as GRio, and, when a range in the tire outer side region Ao having a width corresponding to 25% of the ground contact width CW positioned on the tire equator line side is set as an outer-inner side region Aoi and a groove area ratio in the outer-inner side region Aoi is set as GRoi,
GRoi>GRio
is satisfied.
11. The pneumatic tire according to claim 10 , wherein, when a range in the tire outer side region Ao having a width corresponding to 25% of the ground contact width CW positioned on the tire equator line side is set as an outer-inner side region Aoi and a groove area ratio in the outer-inner side region Aoi is set as GRoi, and, when a range in the tire outer side region Ao having a width corresponding to 25% of the ground contact width CW positioned on a tire width direction ground contact edge side is set as a tire outer-outer side region Aoo and a groove area ratio in the outer-outer side region Aoo is set as GRoo, a relationship
GRoi>GRoo
is satisfied.
12. The pneumatic tire according to claim 11 , wherein the two circumferential main grooves are provided in a center region Ac centering on the tire equator line and having a width of 40% of the ground contact width CW.
13. The pneumatic tire according to claim 12 , wherein
width direction grooves extending in a direction crossing the tire equator line are provided in the tread part, and
the width direction grooves are inclined relative to a tire width direction.
14. The pneumatic tire according to claim 13 , wherein
the width direction grooves include a width direction groove provided in the tire outer side region Ao and a width direction groove provided in the tire inner side region Ai; and
an angle of inclination of the width direction groove provided in the tire outer side region Ao is greater than an angle of inclination of the width direction groove provided in the tire inner side region Ai.
15. The pneumatic tire according to claim 14 , wherein, in the tire inner side region Ai and the tire outer side region Ao, the two circumferential thin grooves are provided in shoulder regions As each having a width of 15% of the ground contact width CW from a ground contact edge to the tire equator line in the tire width direction.
16. The pneumatic tire according to claim 15 , wherein sipes extending in a direction crossing the tire equator line are provided in the tire inner side region Ai.
17. The pneumatic tire according to claim 1 , wherein 0.27<SW/OD <0.3.
18. The pneumatic tire according to claim 17 , wherein 21%<GR<25%.
19. The pneumatic tire according to claim 1 , wherein 21%<GR<25%.
20. The pneumatic tire according to claim 1 , wherein a second land portion formed between one of the two circumferential main grooves and one of the two circumferential thin grooves comprises a block row.
21. The pneumatic tire according to claim 1 , wherein shoulder lug grooves of the tire inner side region extend to the ground contact edge and terminate within the tread part without extending to one of the two circumferential main grooves.
22. Then pneumatic tire according to claim 21 , wherein shoulder lug grooves of the tire outer side region communicate with one of the two circumferential main grooves.
23. The pneumatic tire according to claim 1 , wherein lug grooves provided in the tread part are straight along an entire length of the lug grooves.
24. The pneumatic tire according to claim 23 , wherein all of the two circumferential main grooves, the two circumferential thin grooves, and the lug grooves provided in the tread part are straight.
25. The pneumatic tire according to claim 1 , further comprising an intermediate land portion between the land portion formed between the two circumferential main grooves and a shoulder land portion in the tire inner side region, the intermediate land portion comprising:
lug grooves extending from one of the two circumferential thin grooves and terminating within the intermediate land portion without communicating with one of the two circumferential main grooves; and
sipes extending from the one of the two circumferential main grooves and terminating in the intermediate land portion without communicating with the one of the two circumferential thin grooves;
wherein the sipes and the lug grooves in the intermediate land portion are alternately disposed in the tire circumferential direction.