| 摘要 |
PROBLEM TO BE SOLVED: To provide a pneumatic radial tire having good lightweight property, excellent controllability and stability at high speed, and uniformity. SOLUTION: The pneumatic radial tire is provided with a bead part 11, a side wall part 12, and a crown part 13, and reinforced by a carcass layer 1 and a belt layer 2. The reinforcing cord of the carcass layer 1 is a PK fiber cord formed by twisting filament bundles made of aliphatic polyketone, and satisfies a condition of formulas (I), (II),σ≥-0.01×E + 1.2 ; andσ≥0.02 (wherein E is an elastic modulus in the case of a 49N load at 25°C,σis heat contraction stress at 177°C), and the twisting direction of the reinforcing cord of the carcass layer is different by every strand of cord. COPYRIGHT: (C)2008,JPO&INPIT
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