Patent ID: 7513283

Claim:
A heavy duty tire, comprising: a carcass ply including a ply main body portion and ply turnup portions, wherein the ply main body portion extends over sidewall portions to bead cores of bead portions while the ply turnup portions continue from the ply main body portion and are turned over from inward to outward in a tire axial direction around the bead cores, each of the ply turnup portions includes a main portion and a sub-portion, the main portion curving along an axially inner surface a radially lower surface, and an axially outer surface of the bead core, the sub-portion continues from the main portion and extends straight towards the ply main body portion in the vicinity of a substantially flat radially upper surface of the bead core, while inclining at an angle θ larger than 0° with respect to the upper surface of the bead core so that a distance between the tip end of the sub-portion and the upper surface of the bead core is within the range of 1.0 to 10 mm, the ply turnup portion is turned over around the bead core in a smooth curve; an auxiliary cord layer is provided radially outside the sub-portion in each of the bead portions for pressing the sub-portion; a filling rubber having a complex elastic modulus of 5 to 15 MPa is disposed in each of the bead portions between the sub-portion and the upper surface of the bead core; a reinforcing rubber layer coats each of the bead cores at a coating thickness of 0.5 to 3.0 mm, the reinforcing rubber layer being made of a high modulus rubber having a complex elastic modulus E*a of 20 to 70 MPa, and at an adjacent position at which bead wires of the bead core and carcass cords of the carcass ply are closest, a rubber thickness of a clearance portion between the bead wires and the carcass cords is not less than 0.7 mm, the clearance portion includes a cushion rubber layer interposed between the reinforcing rubber layer and the carcass cords, the cushion rubber layer is made of a low modulus rubber having a complex elastic modulus E*b smaller than the complex elastic modulus E*a of the reinforcing rubber layer, and the difference (E*a−E*b) therebetween is not less than 10 MPa.