| 摘要 |
PURPOSE:To improve the durability of a tire on a dry road and so forth while securing its ice performance by specifying respectively the ratio of groove area in a tread surface, the number of the pitches and their area ratio in a block arrange in a central portion and a shoulder portion, the number of cuts formed in the block and so on. CONSTITUTION:In the tread surface of a tire, plural blocks 3 are formed out of plural main groove 1 and plural sub grooves 2 crossing them. At the central portions 3C of respective block 3, one cut 4 in a radial direction is disposed, and at a shoulder portion 3S, three cuts 4 in a radial direction are disposed respectively. The ratio of groove area in the tread surface is established as 34%-38%. The ratio of total pitches in the central portion 3C and a shoulder portion 3S is established as 2:1 and the area ratios in the central portion 3C and the shoulder portion 3S per pitch are established as 1:1.6-1:1.9 respectively. The groove width of sub groove 2 in the shoulder portion 3S is established as at least 80% of the groove width of the main groove 1. |
