| 摘要 |
PURPOSE:To improve traction performance on ice and brake performance on ice while block rigidity is prevented from lowering by forming sipings, extending in the direction of the width of a tread and having a given depth compared with that of a narrow groove, in the shoulder block of a tire in addition to narrow grooves extending in the direction of the width. CONSTITUTION:Narrow grooves 2 extending throughout the whole of the width of a block are formed approximately in the central position in the peripheral direction of a tread, of a block 1, and at least one siping 3 in the direction of length extending in the peripheral direction of a tread from the side wall of the block on the tread end side is formed. Further, a plurality of sipings 4 in the direction of width opening to a side wall 1a, on the central part side of a tread, of the block 1 are formed in positions separated from each other in the peripheral direction of the tread with the narrow groove 2 therebetween. Provided the depth of the siping 4 in the direction of width is h2 and the depth of the narrow groove 2 is h1, a difference h1- h2 therebetween is set to 0.75h1>=h1- h2>=0.3h1, and a relation between the depth h, of the siping 4 in the direction of width and a depth H of the siping 3 in the direction of length is set to H>=h2. A relation between an overall length L, in the peripheral direction of the tread, of the siping 3 in the direction of length and an average length (l) of the block is set to L>=0.5l. |
