| 摘要 |
PURPOSE:To decrease pattern noise by providing Iongitudinal and transverse grooves, which cross with each other, on a tread portion, and by setting a pitch of the transverse grooves so that a product of the pitch by integer is almost equal to ground contact length under normal condition. CONSTITUTION:On a tread portion T of a tire 1, there are plural longitudinal grooves G, which are continuously elongated in the peripheral direction of the tire. Consequently, the tread portion T is divided into a central rib R1, an intermediate rib R2 and a shoulder rib R3, respectively. Moreover, on the tread portion T, there are plural transverse grooves Y which are elongated so as to cross with each longitudinal groove G. In this case, a pitch P1 of an inner transverse groove Y1 formed on the intermediate rib R2 is determined so as to be uniform. In addition, a product l1 of the pitch P1 of the transverse groove by integer is determined so as to be almost equal to ground contact length L of the tire 1 under normal condition. In this way, sound pressure waves generated at the moment of contact and separation of the transverse grooves Y with a road surface interfere with each other. As the result, noise can be decreased. |
