| 摘要 |
PURPOSE:To enhance the performance of a tire, by providing a transverse main groove, whose width decreases gradually but whose inclination angle increases gradually as the position comes near the tread-width end and which is not connected to a circumferential main groove, in a symmetrical manner on both sides of the circumferential main groove provided in the central area of the tire in the circumferential direction and specifying the radius of curvature of the crown part. CONSTITUTION:A circumferential main groove 1 is provided in the central area of a tire, while transverse main grooves 2 are provided in a symmetrical manner on both sides of the main groove 1, extending toward the tread-end B of the tire. The angle of the transverse main groove 2 to the equatorial plane A is gradually increased to a predetermined angle range, say, from 5 deg. to 80 deg., in the range from the equatorial plane A to the tread-end B. In addition, the width of the transverse groove 2 is gradually decreased from width 'a' at the equatorial plane A to width b at the tread-end B; as, for example, a=7 mm and b=4 mm. In arranging this transverse main groove 2, care should be taken that the groove 2 is not opened to the main groove 1. The radius of curvature of the crown part of the tire is set at 200 mm and under. With this constitution, the steering stability can be enhanced, while a problem of shimmy or of blow can be solved. |
