| 摘要 |
PROBLEM TO BE SOLVED: To provide a pneumatic radial tire having a durable belt layer constituted of an untwisted steel code comprising a plurality of aligned element wires and to improve processing workability of a rolling sheet. SOLUTION: The belt layer of the pneumatic radial tire is constituted of an untwisted steel code comprising 2 to 5 aligned element wires and a diameter d of the respective wires is 0.15 to 0.40 mm. A curvature radius R of residual circular propensity of the element wires is 350 mm or more and a residual rotation characteristic value B provided by a formula (1) of the belt layer is 25 or less. B=¾32π(Σdn<SP>4</SP>×Tn)¾×E wherein dn indicates a diameter (mm) of the n-th element, Tn indicates a residual rotation value of the n-th element (rotations per 6 m), and E indicates code placing density (codes per 50 mm). COPYRIGHT: (C)2004,JPO
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