| 摘要 |
PURPOSE:To improve ice performance at the beginning of abrasion by forming an inner rubber layer of harder rubber than that of an outer rubber layer, constituting a tread, coating the surface of the outer rubber layer by rubber having smaller foaming ratio than it and forming the striations of specific groove depth on the surface of a land part. CONSTITUTION:A tread 6 is constituted of two rubber layers 11, 12 disposed in an outside and an inside in the radial direction of a tire 1. In this case, the inner rubber layer 12 is formed of rubber having Shore A hardness higher than that of an outer rubber layer 11 and a foaming ratio smaller than that of the outer rubber layer 11. the surface of the tread 6 and the surface of the outer rubber layer 11 are coated by a coating rubber layer 21 consisting of rubber having the foaming ratio smaller than that of the outer rubber layer 11. On the surface of a land part 18 in the tread including the outer rubber layer 11, are formed many striations 22 substantially parallel to the axial direction of the tire 1. The depth D of each of striations 22 is set to a value smaller than 4.5mm. |
