| 摘要 |
PURPOSE:To eliminate irregular wear generated at land parts by bending each circumferential groove so that corner acute angle side cross angles formed by the circumferential groove and inclined grooves in a center land part are substantially equal in a circumferential block row. CONSTITUTION:Tread patterns are formed by inclined grooves 2 inclined by an angle theta in relation to the meridian (m) toward the center from both ends (e) of the tread 1, circumferential grooves 3 intersecting the nearly center positions of the inclined grooves 2, a circumferential center groove 4, and land parts 5 divided by these grooves. The land part 5 is formed of a shoulder land part 51 and a center land part 52. The pitch ratio of the pitches p1-p3 of the inclined grooves 2 is 7:9:11, and the circumferential groove 3 is bent so that the angles theta1, theta2, theta3 of the acute angle corner parts of the center land part 52 formed by the circumferential groove 3 and the inclined grooves 21, 22, 23 included in the respective pitches are substantially equal. Irregular wear generated around the acute angle corner parts is thereby prevented, and the setting of the pitch ratio for the decrease of pattern noise is facilitated while improving durability. |
