| 摘要 |
PURPOSE:To improve the properties for partial abrasion resistance and weight grip by a method in which a cutting is equipped from a main groove to a tread end with the angle crossing the equatorial surface of a tyre at the shoulder with a ribrag type tread where blocks are formed by a zigzag main groove and subgrooves. CONSTITUTION:A tread-central part 5 and a shoulder part 6 are formed by the zigzag main groove 4 on a pair of left and right shoulders. Then, cuttings 9 are equipped from the shoulder-main groove 4 to a tread end TE with the direction crossing the equatorial surface C of a tyre at the shoulder part 6 of the tread part 1 where blocks 3a, 3b are formed by the subgrooves 2 opening to the tread end TE from the main groove 4. The depth of the cutting 9 is determined to be 100-20% of the depth of the main groove 4 and the angle alpha between the tyre-peripheral surface and the cutting 9 is caused to be 45-90 deg.. Consequently, partial abrasion is prevented and the property for weight grip is improved without decreasing the rigidity of the tread unsuitably. |
