Bridgestone Corporation

Yukihiro Kiwaki

Keiichi Kato

Takaaki Kojima

Shungo Fujita

Ryoichi Watabe

Naotoshi Aoki

Takamitsu Nakamura

Naoya Ochi

Fumio Takahashi

Ichiro Takahashi

Kenichi Shibata

Kenjiro Yamaya

Yoshiyuki Waki

Shu Nagai

Takanari Saguchi

Kazuyoshi Tagawa

Shu Fujiwara

A pneumatic tire comprising on a tread surfacea plurality of blocks, wherein: the blocks have an inclined grooveformed thereon; the inclined groove has a connecting portionconnected to the circumferential main grooves, a wide-width portionconnected to the connecting portion, and a narrow-width portionconnected to the wide-width portion; the wide-width portion and the narrow-width portion have inclination angles with respect to the tire circumferential direction smaller than the connecting portion; the blocks have a sipeformed thereon, the sipe having one end opening to the connecting portion and the other end opening to the circumferential main grooves; and the sipe has a bent portion.

Pneumatic tire

A pneumatic tire is provided that has enhanced traction performance. A shoulder main body portion of a first shoulder block is formed with a step portion projecting out in a tire circumferential direction. A height of the step portion is set lower than a height of a tread face of the shoulder main body portion and higher than the height of a lug groove. The step portion extends from a tire equatorial plane side end portion of the shoulder main body portion, beyond a tire width direction ground contact edge, to a tire shoulder portion.

A pneumatic tire, while achieving excellent drainage performance by projections and depressions formed in a circumferential groove, can reduce road noise by making the circumferential stiffness of a land portion uniform even in the presence of such projections and depressions. A plurality of protuberances are arranged in at least one circumferential groove at intervals in the tread circumferential direction, the protuberances being raised from the inner surface of the circumferential groove and extending from the groove bottom of the circumferential groove to at least one groove wall surface in the tread width direction. A plurality of sipes are arranged in a land portion adjacent to the groove wall surface of the circumferential groove to which the protuberances extend, the sipes being open to the circumferential groove in areas where the respective protuberances are arranged.

Tire tread

A tire includes a circumferential direction main groove on a tread surface, first and second circumferential supplemental grooves located on both sides of the circumferential direction main groove, and first and second central land portions formed between the circumferential direction main groove and the first and second circumferential direction supplemental grooves. The first and second central land portions have plural width direction sipes, respectively, and each of the width direction sipes extends to the circumferential main groove, the circumferential main groove has shallow grooved portions and deep grooved portions. The deep grooved portions are deeper than the shallow grooved portions, and the shallow grooved portions are shallower than the circumferential supplemental grooves.

Tire

This tire has a buttress section to which a plurality of depressions () have been formed along the tire peripheral direction (D). The depressions () have: a first outer edge () that bulges inward in the tread width direction (D); and a second outer edge () that is continuous with the first outer edge () and that bulges outward in the tread width direction (D) with respect to the first outer edge (). The distance between the deepest section () of the depressions () and the ground-contact end of the tread varies along the tire peripheral direction (D).

A tire wherein a first bulge part and a second bulge part are formed in a circumferential direction groove. The first bulge part has a narrow-tip shape such that, in the tire tread plan view, the size in the tread width direction diminishes along a first direction in the tire circumferential direction. The second bulge part has a narrow-tip shape such that, in the tire tread plan view, the size in the tread width direction diminishes along a second direction opposite to the first direction in the tire circumferential direction. A plurality of first bulge parts and second bulge parts are provided at predetermined intervals in the tire circumferential direction. A groove part which extends in the tire circumferential direction is provided between the first bulge part and the second bulge part which opposes the first bulge part in the tread width direction.

A pneumatic tire which comprises a land portion () and a land portion (). A main groove () extending along the tire circumferential direction is formed between the land portion () and the land portion (). The land portion () comprises a groove wall () that forms the main groove (). The land portion () comprises a groove wall () that forms the main groove (). The groove wall () and the groove wall () are serpentine along the tire circumferential direction (R) when seen from a plane of the tread surface, and the groove width of the main groove () in the tread width direction (W) varies in a predetermined repetition interval (&#x3bb;) along the tire circumferential direction. The ratio of the minimum width (W) of the groove to the maximum width (W) of the groove satisfies a relation of 35%&#x2266;W/W&#x2266;85%.

Pneumatic tire with main groove having serpentine groove walls

Tread portion of an automobile tire

The pneumatic tiresatisfies both SW&#x2266;175 mm and OD/SW&#x2267;3.6, where SW is the width of the pneumatic tireand OD is the outer diameter of the pneumatic tire. Moreover, the pneumatic tiresatisfies both SW&#x2266;175 mm and OD/RD&#x2266;1.4, where SW is the width, OD is the outer diameter, and RD is the inner diameter of the pneumatic tire, which is the diameter of a portion of the pneumatic tire(an end portion of a bead portion) in contact with a wheel in a state where the pneumatic tireis fitted to the wheel.

Both wet weather performance and steering stability performance are achieved. Lateral main grooves () formed in a tread () extend in a direction intersecting with circumferential main grooves () and open onto the circumferential main grooves (). Water between the tread () and a road surface during wet weather running is accordingly discharged through the lateral main grooves () to the circumferential main grooves (). The end portions of the lateral main grooves () opening onto the circumferential main groove () are provided with intersection portionswhere first land portions () and second land portions () adjacent to each other in the tire circumferential direction at a lateral main groove () support each other in the tire width direction. The end portions at the circumferential main groove () side of the first land portions () and the second land portions () do not therefore readily tilt over even when a large slip angle is imparted to the tire.

A tire provided with a plurality of land portions formed by a main groove extending along a tire circumferential direction, wherein the main groove is formed with one intra-groove recessed in a tire inner direction from a surface of the main groove, the intra-groove comprises: a first circumferential groove portion extending along the tire circumferential direction on the first groove wall; a first inclined portion extending from the first groove wall toward the second groove wall on a groove bottom of the main groove; a second circumferential groove portion extending along the tire circumferential direction on the second groove wall; and a second inclined portion extending from the second groove wall toward the first groove wall on the groove bottom of the main groove.

Growing community of inventors

Tokyo, Japan

Yukihiro Kiwaki