JP2724291B

PURPOSE: To effectively improve durability of a bead part and to reduce the weight of the bead part. CONSTITUTION: This tire has a main part A straddling bead cores 5, 5, a winding up part B for winding the bead core 5 from inside to outside, a carcass 6 in which the carcass codes made of steel are arranged and a bead apex rubber 10 going between the main part A of the carcass 6 and the winding-up part B and upwards from the bead core 5. In a state where the tire is set in a standard rim and inner pressure is set at 0.5ksc, a ply center line J in the range between an upper contacting point P1 at which a main part A9a of a carcass ply 9a nearest to the inner space H of a tire comes near the outer end point 13 of the bead apex rubber 10 and a lower contacting point P2 at which the main part A9a begins separating from the bead core 5 forms a nearly straight line whose maximum deviation V from a line X connecting the upper contact point P1 and the lower contact point P2 and having a length L in the direction perpendicular to the line X is not more than 0.02 times the length L.