| 摘要 |
PURPOSE:To prevent partial wear to restrain noise by directly connecting sub- grooves intersecting plural block-lines formed by a peripheral groove and the sub-grooves on the ground-contact area of the shoulder part, and specifying the width of the sub-groove of the inside block, the ratio of sectional areas of the inside and outside blocks, and the ratio of the length of the sub-groove of the inside block to the length of the sub--groove to the ground contact end. CONSTITUTION:Two inside and outside block lines 31, 32 of plural block-lines formed by a main groove and sub-grooves on the tread part are formed on the ground contact area of a shoulder, and the sub-grooves 21, 22 intersecting the block-lines are directly connected to each other. The groove-width y of the inside sub-groove 22 ranges from 1.0 to 2.5mm, and the ratio A/B of the groove-sectional area A of the inside sub-groove to the groove-sectional area B of the outside sub-groove 21 is set at 0.6 or less. Further, the ratio l/D of the length l of the inside sub-groove to the length D of the sub-groove from the inside end to the ground contact end is set at 0.5 or lees. In this constitution, partial wear can be prevented to reduce high frequency noise. |
