| 摘要 |
Provided is a pneumatic radial tire including a main belt layer and at least one circumferential-direction reinforcement layer, which are provided in the tread portion. The main belt layer includes two belt layers in which steel cords are disposed in a manner that the steel cords of a first one of the two belt layers intersect the steel cords of a second one of the two belt layers. In the circumferential-direction reinforcement layer, steel cords are disposed in a substantial tire circumferential direction. The ratio Wo/Wm of the width Wo of the circumferential-direction reinforcement layer to the maximum width Wm of the main belt layer is 0.5 to 0.9. The ratio Ee/Ec of the reinforcement-cord elastic modulus Ee of the steel cords in the edge portions of the circumferential-direction reinforcement layer to the reinforcement-cord elastic modulus Ec of the steel cords in the center portion of the circumferential-direction reinforcement layer is not less than (0.85-0.5 Wo/Wm) and not more than 0.8.
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