Pneumatic radial tires with one-piece molded stiffener having at least two rubber compositions of different hardness

A pneumatic radial tire comprising;

• a radial carcass having a rubberized cord ply extending between a pair of bead cores, each bead core embedded in a bead portion for reinforcing a sidewall portion of said tire and a tread portion, said carcass comprised of a main body portion reinforcing the above portions and a turnup portion wound around each bead core from inside toward outside, and a stiffener arranged in each bead portion between the main body portion and the turnup portion of the carcass and taperingly extending from the bead core toward the tread portion along the main body portion of the carcass, the stiffener comprising one-piece molded body of at least two rubber compositions having different hardnesses, and a rubber composition having a highest hardness among these rubber compositions is arranged close to the main body portion of the carcass as a deformation-isolating rubber member having a greatest thickness at a position separated from a line (Lv), which is drawn perpendicular from an end of the turnup portion toward an outer surface of the carcass main body portion in tire cross-section, at least in a side of the tread portion among both sides sandwiching the line (Lv), and a rubber composition having a hardness lower than that of the rubber composition having the highest hardness is arranged along an inner surface of the turnup portion.