| 摘要 |
PURPOSE:To improve running characteristics on ice and snow and at the same time, improve wear resistance and resistance against a uneven-wear on running on ordinary roads by carving cuttings on a block after a raw cover tire is vulcanizated and specifying the ingredients and the compsn. of a tread part. CONSTITUTION:A block 4 divided by a tread groove 3 is formed and the ratio of the total area Sg of the tread groove on the grounding face to the area Sl of the grounding face is made 0.25 or larger. On the other hand, a raw cover tire is formed wherein a transverse groove (g) has a side edge part with a length of at least 12.7mm or larger from the end edge to the tire center side and a groove width in the tire circumferential direction of 1.59mm or larger and the side edge part is inclined in an angle range of 35-90 deg. to the tire circumferential direction and the rubber in the tread part 2 after vulcanization exhibits a glass transition temp. of -60 deg.C or higher and -50 deg.C or lower by valcanizing the cover tire. In addition, the rubber exhibits a JIS A hardness at -5 deg.C of 60 or larger and 72 or smaller and after vulcanization, cuttings 9 extending in the tire circumferential direction are formed on the block 4 in parallel and at intervals in the tire circumferential direction. |
