Bridgestone Corporation

Bridgestone Tire Company Limited

Masanobu Takahashi

Kenshiro Kato

Shigeki Yamada

Motoaki Taniguchi

Kazuyuki Endo

A heavy duty radial tire comprises a tread portion, a pair of sidewall portions, a pair of bead portions, a carcass of at least two plies and a breaker, wherein each ply is composed of cords of aromatic copolyamide fiber having particular units A and B and a specific rubber composition having 100% modulus of 35-50 kg/cm.sup.2.

Heavy duty pneumatic radial tires with carcass plies composed of

A heavy duty pneumatic radial tire for use in airplanes and the like is disclosed, which comprises a toroidal radial carcass, a belt superimposed about a crown region of the carcass, and a bead portion reinforcement comprised of a main chafer made from aromatic polyamide fiber cords, and an auxiliary chafer of at least two outer cord layers and at least two inner cord layers having a triangular truss structure defined by three cord layers among such four cord layers that the cords of the two outer cord layers are crossed with each other with respect to the meridional plane of the tire and the cords of the two inner cord layers are crossed with each other with respect to the meridional plane.

Heavy duty pneumatic radial tires

A heavy duty pneumatic radial tire for use in airplanes and the like is disclosed, which comprises a toroidal radial carcass, a belt superimposed about a crown region of the carcass and composed of at least three cord layers, and a bead portion reinforcement consisting of a stiffener composed of a hard rubber stock and a soft rubber stock, a main chafer made from aromatic polyamide fiber cords, and an auxiliary chafer of at least two cord layers covering the outside of said main chafer and at least one cord layer arranged along the inside of the turnup portion as an inner cord layer, and having such a triangular truss structure that cords of at least two cord layers are arranged at inclination angles of 65.degree..about.90.degree. and 35.degree..about.55.degree. with respect to the meridional plane of the tire, respectively, and cords of the remaining cord layer are arranged at an inclination angle of -50.degree..about.70.degree. with respect to the meridional plane.

A heavy duty pneumatic tire having an improved durability is disclosed. This tire comprises a carcass of a bias structure composed of at least 12 rubberized laminated ply layers each containing organic fiber cords embedded therein, and divided into three inner, middle and outer ply groups by three bead cores, the cords of which are crossed with each other, as a reinforcement for a toroidal casing inclusive of a tread. In a region extending from an upper area of a bead portion of the casing within a range of 0.15 to 0.45 times a tire height as measured from a bead base of the tire, at least an average cord distance between adjacent ply layers at the middle and outer ply groups is made substantially wider than at the inner ply group and a cord distance between adjacent ply layers at the outer ply group is made substantially not more than at the middle ply group.

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Iruma, Japan

Masanobu Takahashi