| 摘要 |
PROBLEM TO BE SOLVED: To improve resistance to flex break. SOLUTION: Rate of change (RA'-RA)/RA of a diameter of a contacting end of a tread 24 between a free state and a state where internal pressure is filled is set between 4 to 14%, and a rate of change (WB'-WB)/WB of a tire maximum width portion is set between -21% and -4%. Accordingly, the change rate of the tire maximum width between free state and the state filled with internal pressure is greater as compare to conventional tires. Because the diametral change of the contact end portion is increased, the tension of the carcass cord of a flex zone at internal pressure filled state can be increased and a tensile strain is increased. This reduces compressive strain of the carcass cord of the flex zone (range between contact end A' and tire maximum width portion B'), thus drastically improving resistance to flex brake (breakage of cord).
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