Heavy duty radial tire

A tire and rim assembly comprising a radial tire and a rim on which said tire is mounted,

• said tire comprising
• a pair of bead portions with a core,
• a tread portion,
• a pair of sidewall portions extending between the tread edges and the bead portions,
• a carcass composed of at least one ply of organic fiber cords arranged radially at an angle of 90 to 75 degrees to the equatorial plane of the tire extending across the bead portions and turned up around the bead cores from the axially inside to the outside thereof to form two turned up portions and one toroidal main portion of the carcass,
• an annular tread disposed radially outside the carcass to define said tread portion, and
• a breaker composed of at least two plies of cords disposed between the tread and the carcass,
• said rim comprising
• a bead seat on which each bead portion of the tire is seated, and
• a flange extending radially outwardly from the axially outer edge of said bead seat, wherein
• in the condition where the tire is not mounted on the rim, each of said bead portions is provided with a bottom face composed of an axial inner face and an axial outer face, each tapered axially inward to decrease the diameter of the bottom face,
• the taper angle (beta) of said inner face being larger than the taper angle (alpha) of said outer face, said angle (alpha) corresponding to the inclination angle of the bead seat of the rim, and
• the boundary between the inner face and the outer face is located axially inward of the center of gravity of the bead core, and wherein
• in a condition where the tire is mounted on said rim and inflated to normal tire pressure, the bead core in each bead portion is positioned to satisfy the following conditions:
• the axial distance (X) from the axially inner edge (Q2) of the bead core to the bead heel (Q1), defined as the intersection between a base line (B) of the rim and an extended line of the inner surface of the rim flange, is not less than 80% and not more than 105% of the height (HR) of the radial outer edge (Q3) of the rim flange from the base line;
• and
• the radial distance (Y) from the radially outer edge (Q4) to the bead core measured radially inwardly from the radially outer edge (Q3) of the rim flange is not less than 0% and not more than 30% of the height (HR) of the rim flange from the base line.