| 摘要 |
PROBLEM TO BE SOLVED: To solve problems that a crack develops at the upper end of a carcass formed by winding up the periphery of a bead core in a radial tire, and tire weight is increased by adding or thickening a reinforcing layer in the bead part in order to prevent the occurrence of the crack. SOLUTION: Respective connection points (middle points) 13, 16 of a cross section curve having a moderate S shape are positioned in the radially inward part of the tire in inside and outside case lines 12, 15 of a carcass 3, thereby reducing shearing strain near a rim flange 18. A tire side part 7 is shaped in an outer swelling shape around the bead part 2 as a base point to increase deflection of the tire side part 7, thereby improving stress dispersion at the winding up end of the carcass 3. As a result, the development of the crack is prevented and tire durability is improved. Ride comfortableness is improved. The reinforcing layer is not added or thickened.
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