| 摘要 |
PROBLEM TO BE SOLVED: To provide a studless pneumatic tire excellent in on-icy-road travel performance. SOLUTION: A tread is made into a cab-and-base structure consisting of base rubber and cap rubber, and sipes 20, 21 are formed in the raised block 18 of the tread. In order to compensate for a decrease in block rigidity due to the formation of the sipes, the raised block 18 is designed so that where the sipes are arranged, its portion where the total projected length of the sipes is long has a higher volume ratio of the hard base rubber to the soft cap rubber than its portion where the total projected length is short. Thus the block rigidity of the raised block 18 is secured, and for heavy-load tires such as those for trucks and buses, chipping of the block can be prevented; for passenger-car tires, raised elements subdivided by the sipes are restrained from collapsing during cornering, thus securing steering stability.
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