Patent ID: 7165590

Claim:
A heavy duty pneumatic radial tire including a carcass ply, in which a ply folding portion folded from inside to outside in a tire axial direction around a bead core is successively disposed in a ply body extending from a tread to the bead core in a bead via a sidewall; the ply folding portion including a main portion folded along an inside surface in the tire axial direction of the bead core, a lower surface in a radial direction and an outside surface in the tire axial direction, and a winding-up portion extending continuously to the main portion and apart from the bead core; wherein the winding-up portion having an intervening filled rubber between an upper surface in a radial direction of the bead core, extends with an inclination of an angle θ in a direction in which a diameter is increased inward in the tire axial direction in a state in which a tire is rimmed in a regular rim and an inner pressure of 50 kPa is filled, the angle θ being set to 20 to 65 degrees with respect to an upper surface in the radial direction of the bead core, a distance La from the upper surface in the radial direction of the bead core at the inner end point of the winding-up portion being set to 5 mm to 15 mm, and a distance Lb between the inner end point of the winding-up portion and the ply body being set to 1 mm to 5 mm, and the bead core has a core maximum width W of 15 mm to 19 mm, the ratio La/W of the distance La from the upper surface in the radial direction of the bead core at the inner end point of the winding-up portion to the core maximum width W ranging from 0.26 to 0.80.