Bridgestone Corporation

Bridgestone Tire Company Limited

Kenji Karato

Hideaki Nishio

Hiroshi Kojima

Masao Nakamura

Automobile tire

A heavy duty pneumatic radial tire is disclosed, which comprises a tread portion, a pair of side portions, a pair of bead portions each reinforced with a bead ring, a radial carcass ply, a metal cord reinforcing layer and a composite rubber filler. In this tire, the carcass ply is a rubberized layer of aromatic polyamide fiber cords and a tip of its turnup portion terminates at a position lower than an upper end of a rim flange when the tire is mounted on a rim. In the metal cord reinforcing layer, one end facing the turnup portion terminates over the tip of the turnup portion and the other end facing the carcass ply extends toward the side portion over a position corresponding to the above-mentioned one end facing the turnup portion. The rubber filler consists of a hard rubber stock and a soft rubber stock, wherein the hard rubber stock extends above the bead ring along the carcass ply over a position corresponding to the end of the reinforcing layer facing the carcass ply, and the soft rubber stock extends toward the side portion over the hard rubber stock between the hard rubber stock and the reinforcing layer facing the turnup portion and the lower end thereof locates between the hard rubber stock and the turnup portion in a wedge shape.

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Tokyo, Japan

Kenji Karato