Pneumatic radial tires with stiffeners composed of three stiffener members

A pneumatic radial tire comprising;

• a pair of bead cores, at least one radial carcass ply comprised of a main body extending between the bead cores and a turnup portion wound around each bead core from inside toward outside, a stiffener arranged between the main body and the turnup portion of a radially outermost carcass ply and extending from each bead core along the main body outward in substantially a radial direction of the tire, said stiffener composed of first, second and third stiffener members successively arranged from inside toward outside in the radial direction and made from rubbers being lower in hardness in this order, and a boundary surface X between the first and second stiffener members being inclined outward in the radial direction to approach to the main body and a boundary surface Y between the second and third stiffener members being inclined outward in the radial direction to separate away from the main body, and a ply end rubber member made from rubber having a hardness between the hardnesses of the first and third stiffener members arranged on an outer end region of the turnup portion in the radial direction, and an outer end Y1 of the boundary surface Y between the second and third stiffener members in the radial direction being located outward from an outer end of the ply end rubber member in the radial direction and an inner end X1 of the boundary surface X between the first and second stiffener members in the radial direction being located inward from an outer end of the turnup portion in the radial direction.