| 摘要 |
PURPOSE:To provide improved high-speed driving durability without deteriorating maneuvering stability and partial wear resistance by forming a tread from composite of a cap rubber layer arranged on the ground contact side, and a base rubber layer whose loss tangent is smaller than one of the cap rubber layer arranged on the inner side in the diametrical direction. CONSTITUTION:A prescribed tread pattern is formed on the surface of a tread 11. With this constitution, rubber which constitutes the tread 11 is formed into a two-layer structure of a cap rubber layer 12 arranged on the surface side coming into contact with the ground, and a base rubber layer 13 arranged on its inner side. Besides, the cap rubber layer 12 is connected with the land part of the tread 11 by a thin bridge 12a. On the other hand, the base rubber layer 13 occupies the part between the cap rubber layer 12 and a belt layer 10, and a protruding part 14 which protrudes toward the inside of a rib 7 is provided facing the center of the tread. Besides, in order to improve high-speed durability, the loss tangent of the base rubber layer 13 is made smaller than one of the cap rubber layer 12, for example, whose loss tangent is less than 60% of that of the cap rubber layer 12, that is to say concretely, 0.1-0.3 loss tangent, which provides more profitable workability. |
