| 摘要 |
PROBLEM TO BE SOLVED: To remove bead part reinforcing materials such as wire-chaffer or nylon chaffer to reduce cost, reduce the weight, and improve the productivity, and improve the durability by optimizing the wall thickness and shape of bead parts. SOLUTION: A bead part-inflection point at which a carcass line is changed from an outwardly protruded curve to an inwardly protruded curve, is represented by P, and a central point of rim-flange circular arc part in state where the tire is loaded in a normal rim and the tire is filled with a normal internal pressure, is represented by Q. When a rim-oppositional point is represented by R at the time when a normal load is statically applied to the tire, an inclined angleθof a straight line connecting the inflection point P with the central point of the rim-flange circular arc part to the direction of tire rotatary shaft, is 20 or 40 degrees. A B/A ratio of the distance B between the carcass body and the folded part of the carcass on a perpendicular line drawn to the carcass body through a rim-oppositional point R to the distance A between the carcass body and the folded part of the carcass on a straight line extending through the rim-flange circular arc central point Q at an angle of 45 degrees to the direction of the tire rotary shaft, shall be 40 or 100%.
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