Bridgestone Corporation

Mitsunori Uchida

Junichi Takahashi

A motorcycle pneumatic tire, in which the tread includes a central rubber and a side rubber, having a lower modulus than the central rubber, that are sequentially laminated in both tire widthwise side portions, the side rubber extending to a tire width-direction inner side further than a point at &#xbc; of a tread width on a tire width-direction outer side from a tire equator. A tire ground-contact surface has a tread pattern that includes plural inclined grooves and, when the tread width is equally divided in eight, a region constituting a range of &#xbc; to &#x215c; of the tread width on the tire width-direction outer side from the tire equator has the largest number of inclined grooves included per a single pitch of the tread pattern, and the depth of the inclined grooves is greater than the thickness of the side rubber in at least a part of the region.

Pneumatic tire for motorcycle

Provided is a motorcycle pneumatic tire in which the wet grip performance is improved while the steering stability during turning is ensured. The motorcycle pneumatic tire includes, on its ground-contact surface: a first inclined groove () that extends on a tire width-direction outer side from the vicinity of a tire equator and is inclined in the same direction as a tire rotation direction; and a short groove () that is arranged on the extension of a tire width-direction outer end of the first inclined groove (). The tire width-direction outer end of the first inclined groove is positioned in the vicinity of a point at &#xbc; of a tread width (TW) from the tire equator on the tire width-direction outer side, while a tire width-direction inner end of the short groove is positioned in a range of &#xbc; to 5/16 of the tread width (TW) from the tire equator on the tire width-direction outer side; an inclination angle of the first inclined groove with respect to a tire circumferential direction increases toward the tire width-direction outer side; and an angle &#x3b8;formed by a groove wall of the tire width-direction outer end of the first inclined groove with respect to the direction perpendicular to the tire surface, and an angle &#x3b8;formed by a groove wall of the tire width-direction inner end of the short groove with respect to the direction perpendicular to the tire surface, satisfy a relationship of &#x3b8;&#x3e;&#x3b8;.

Provided is a motorcycle tire having improved wet performance during straight running without compromising other performances. The motorcycle tire is a motorcycle tire whose rotation direction when mounted on a vehicle is designated. A main groove () at least including a first groove () and a second groove () having different inclination directions, and a sub groove () are provided on a tire tread, the main groove and the sub groove are alternately repeatedly formed in the tire circumferential direction line symmetrically with respect to the tire equator and are arranged offset in the tire circumferential direction between one side and the other side in the tire width direction, and the main groove and the sub groove include, per one pitch of pattern on one side in the tire width direction within the contact region S during straight running, two or more outward grooves extending obliquely from the tire equator side to the outside in the tire width direction toward the designated reverse rotation direction of the rotation direction and one or more inward grooves extending obliquely from the outside in the tire width direction to the tire equator side toward the designated reverse rotation direction of the rotation direction.

Growing community of inventors

Tokyo, Japan

Mitsunori Uchida