| 摘要 |
PURPOSE:To seek to decrease rotation resistance and realize low fuel consumption by radially forming specified small grooves at specified pitches which extend outward in the radial direction with a buttress face as the starting point at an edge where a tread earth contact face and the buttress face intersect each other. CONSTITUTION:Small grooves 6 whose widths W are 2-3mm, depths D are 5-10mm and length L in the radial direction are 10-30mm are provided in juxtaposition so that the pitch P between the small grooves 6 may be 10-20mm, at an edge B where an earth contact face 3 of a tread 2 and a buttress face 4 intersect each other. By this constitution, the flexibility of a shoulder part is improved and the edge becomes easy to shift in the circumferential direction as well as in the axis direction with the earth contact of the tyre and aggregative deformation amount of the tread decreases. Hereby, it becomes possible to decrease rotation resistance and fuel consumption without injuring gripping ability.
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