Patent ID: 7513283
Filing Date: 2009-04-07
Classification: B60C,Y10T

Abstract:
1. A heavy duty tire, comprising: a carcass ply including a ply main body portion and ply turnup portions, wherein 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.