| 摘要 |
PROBLEM TO BE SOLVED: To improve the durability of a bead section in a heavy load tire used for heavy load vehicles such as trucks and buses. SOLUTION: This pneumatic tire is provided with a carcass 6 wherein a folding section 66, which is folded outside from the inside of the axial direction of the tire around a bead core 5 integrally, and a belt layer 7 on a body section 6a extending from a tread section 2 to the bead core 5 of a bead section 4 through a side wall section 3. The ratio (R1/R2) of the radius R1 of curvature of the body section 6a of the carcass ply 6A at a place P1 of a height of 0.25 times carcass height Hc, which is separated 0.25 times carcass height Hc from a bead base line BL to the most outside position in the tire radius direction of the carcass 6 with the tire assembled to a normal rim, charged with normal inner pressure and non-loaded and the radius R2 of curvature of the body section of the carcass ply 6A at a place of height of 0.25 times with the tire assembled temporarily to the normal rim, charged with a pressure of 50kPa and non-loaded is made to 0.8 to 1.2. COPYRIGHT: (C)2004,JPO
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