| 摘要 |
PROBLEM TO BE SOLVED: To improve turning performance and abrasion resistance by arranging a belt reinforcing layer, where a cord having a specific tensile elastic modulus is driven at a specific angle into a tire equatorial surface, between a radial carcass and a spiral belt layer, and forming a shape in a no-load condition so as to satisfy the specific relationship. SOLUTION: A pair of bead parts, a radial carcass 14, a tread part 16 and spiral belt layers 20 not less than a single layer are provided. A belt reinforcing layer 22 where a cord on which a tensile elastic modulus at 10% elongating time at a room temperature is not less than 600kg/mm<2> is driven at an angle of 55 to 90 deg. into a tire equatorial surface, is arranged between the radial carcass layer 14 and the spiral belt layers 20. A radius of curvature of a tread of a crown central area of a tread part 16 is set to R1, a radius of curvature of an outside surface of a shoulder area of the tread part 16 is set to R2, a tire maximum width is set to W, and it is installed in a standard rim, and a shape in a no-load condition where standard internal pressure is filled, is formed so as to satisfy (R2×10>=R1>=R2×3 and W×2.0>=R1>=W×0.8).
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