Pneumatic tire
A pneumatic tire includes circumferential grooves aligned in a lateral direction and extending in a circumferential direction, lateral grooves aligned in the circumferential direction and extending to cross the circumferential direction, communicating at ends with the circumferential grooves and defining a block-shaped land portion between the circumferential grooves, two narrow grooves aligned in the lateral direction and extending in the circumferential direction, communicating at ends with a lateral groove and dividing the land portion defined by each of the circumferential grooves and each of the lateral grooves into small land portions, the narrow grooves having a smaller groove width than the circumferential grooves and being formed with a bent portion in an intermediate portion, the bent portion being disposed inward in the lateral direction, and bend points of the bent portions being disposed at positions offset from one another in the circumferential direction.
1. A pneumatic tire, comprising:
a circumferential belt, in a tread portion, disposed in a tire lateral direction encompassing a position of a tire equatorial plane comprising cords extending in a tire circumferential direction disposed in alignment in a tire lateral direction;
a plurality of circumferential grooves, in a tread surface of the tread portion, disposed in alignment in the tire lateral direction extending in the tire circumferential direction, comprising a central circumferential groove disposed on the tire equatorial plane, outer circumferential grooves disposed outermost in the tire lateral direction, and intermediate circumferential grooves disposed between the central circumferential groove and the outer circumferential grooves;
a land portion disposed between the central circumferential groove and one of the outer circumferential grooves being divided into at least three land portions in the tire lateral direction by the intermediate circumferential grooves; and
a plurality of lateral grooves, in each of the land portions, disposed in alignment in the tire lateral direction at an incline with respect to the tire circumferential direction, opening at both ends to the circumferential grooves adjacent in the tire lateral direction; wherein
an inclination angle of an acute angle of the lateral grooves with respect to the tire circumferential direction is smallest in the land portion closest to the tire equatorial plane and is larger in the land portion closer to a tire lateral direction outer side;
each of the at least three land portions are formed to have a plurality of blocks defined by two circumferential grooves adjacent in the tire lateral direction and two lateral grooves adjacent in the tire circumferential direction;
the blocks are divided in the tire lateral direction to form small blocks by a narrow groove that opens at both ends to two of the lateral grooves adjacent in the tire circumferential direction; and
in the plurality of blocks, a surface area S I of the small block closest to the tire equatorial plane and a surface area S O of the small block closest to the tire lateral direction outer side satisfy a relationship 1.03≤S O /S I ≤1.10.
2. The pneumatic tire according to claim 1 ,
wherein the lateral grooves between the two of the land portions adjacent in the tire lateral direction have a difference in the inclination angle being larger closer to the tire equatorial plane and smaller closer to the tire lateral direction outer side.
3. The pneumatic tire according to claim 1 , wherein
a center region is a region defined between the outer circumferential grooves,
a tire lateral direction dimension Wf of the center region and a tire lateral direction dimension Wg of the circumferential belt satisfy a relationship Wg/Wf≥1.03.
4. The pneumatic tire according to claim 1 , wherein
when the pneumatic tire is mounted on a regular rim, inflated to a regular internal pressure, and in an unloaded state, a difference in tire radial direction dimension between both ends in the tire lateral direction of the land portions is smaller closer to the tire equatorial plane and larger closer to the tire lateral direction outer side, and a difference in tire radial direction dimension Do of the land portion located outermost in the tire lateral direction and a difference in tire radial direction dimension Dm of the land portion adjacent thereto inward in the tire lateral direction satisfy a relationship Do/Dm≥1.5.
5. The pneumatic tire according to claim 1 , wherein
the land portions are formed to have a plurality of blocks defined by two circumferential grooves adjacent in the tire lateral direction and two lateral grooves adjacent in the tire circumferential direction; and
an aspect ratio of a tire circumferential direction dimension L and a tire lateral direction dimension We of each of the blocks satisfies 1.2≤L/We≤2.0.
6. The pneumatic tire according to claim 2 , wherein
a center region is a region defined between the outer circumferential grooves,
a tire lateral direction dimension Wf of the center region and a tire lateral direction dimension Wg of the circumferential belt satisfy a relationship Wg/Wf≥1.03.
7. The pneumatic tire according to claim 6 , wherein
when the pneumatic tire is mounted on a regular rim, inflated to a regular internal pressure, and in an unloaded state, a difference in tire radial direction dimension between both ends in the tire lateral direction of the land portions is smaller closer to the tire equatorial plane and larger closer to the tire lateral direction outer side, and a difference in tire radial direction dimension Do of the land portion located outermost in the tire lateral direction and a difference in tire radial direction dimension Dm of the land portion adjacent thereto inward in the tire lateral direction satisfy a relationship Do/Dm≥1.5.
8. The pneumatic tire according to claim 7 , wherein
the land portions are formed to have a plurality of blocks defined by two circumferential grooves adjacent in the tire lateral direction and two lateral grooves adjacent in the tire circumferential direction; and
an aspect ratio of a tire circumferential direction dimension L and a tire lateral direction dimension We of each of the blocks satisfies 1.2≤L/We≤2.0.