| 摘要 |
PURPOSE:To prevent a wound of tread and spread of an external wound by forming a straight groove having a step-like cross section of the specified groove width and depth in a tire circumferential direction at the specified distance toward the tread end from the tire equator. CONSTITUTION:In a radial tire 1 provided with a carcass layer 6 along its inner surface and belt reinforcing layers 8 and 9 facing a tread part 5 on the carcass 6, multi-step main groove 11 (straight groove) is formed along with the circumferential direction of the tire on a tread face 10 of the tread part 5. Calves 12 are provided on the tread 10 both in the circumferential and radius direction of the tire 1. The main groove 11 is provided in the position within 50% of the tread width a/2 between the tire equator CL and a tread edge 13 from the tire equator CL towards the tread edge 13. The rate W/a of the width W of the main groove 11 to the tread width (a) between tread edges is set to 0.07- 0.14, and the rate W/D of the groove width W to the depth D is set to 10-2.0. |
