| 摘要 |
PROBLEM TO BE SOLVED: To reconcile improved straight running stability resulting from shimmy prevention and steering performance. SOLUTION: The crown portion of a carcass 16 is reinforced by a peripheral belt layer 22 as a spiral belt for improving high-speed durability. A tread 28 is formed in a cap-base structure consisting of a high-hardness cap rubber layer 24 and a base rubber layer 26 and the structural flexibility of the spiral belt is reinforced by the high-hardness cap rubber layer 24, so that the shearing rigidity of the tread 28 is maintained in the condition that the tread is so relatively thick as new, high-speed stability, smooth handling and high responsibility are so obtained as new and the occurrence of shimmy is prevented. Since the hardness of the base rubber layer 26 is lower than that of the cap rubber layer 24, the increasing rate of the shearing rigidity of the tread 28, increasing more as worn, is restricted and the change of the shearing rigidity in a period from a new one to a badly worn one, namely, the change of handling performance can be kept to a minimum. |
