| 摘要 |
PURPOSE:To restrain blowout, and to enhance durability, by providing at least one shallow groove parallel to the circumferential direction in the central region of at least one row of blocks, and specifying the depth of the shallow groove and the periphery in the direction of the turning shaft. CONSTITUTION:The flatness of a tire is set to be 0.6 or less, and in the tread part a plurality of block rows S' through S''' are formed by circumferential main grooves 1 and transverse main grooves 2. And the block row S'' in the central region of the tread is formed by blocks 3' of relatively small area. In this constitution, in the central region of the tread at least one shallow grooves S substantially parallel to the circumferential direction is provided. And the depth of the shallow groove S is set to be within maximum 2 mm, and further the peripheries L0, L1 in the direction of the turning shaft of the tire on the outer surface of the block 3' are increased by 1 to 10%, so that the stiffness of the relevant block 3' can be made unchanged. |
