| 摘要 |
PURPOSE:To unify ground pressure at respective parts on a block 15 of which outer surface is formed into a projecting polygon, and improve the dry running performance. CONSTITUTION:The distance C in the radial direction from the bottom 25 of a main groove 13 to the outer surface of a block 15 in the vicinity of a short side 19 at which deformation is easy and ground pressure is low, is set larger than the above-mentioned distance D in the radial direction in the vicinity of a long side 18 at which deformation is hard and ground pressure is high, hereby, a rubber quantity in the vicinity of the short side 19 is increased, meanwhile, a rubber quantity in the vicinity of the long side 18 is decreased, and hence the ground pressure is unified at respective parts of the outer surface of the block 15. |
