Bridgestone Corporation

Bridgestone Tire Company Limited

Kenshiro Kato

Minoru Togashi

Shigeki Yamada

Masanobu Takahashi

Motoaki Taniguchi

Kazuyuki Endo

Shin-ichi Furuya

Kuninobu Kadota

Shinichi Furuya

In a pneumatic radial tire for trucks and buses mounted on an approved 15&deg; drop center rim, an outer surface portion of a composite side-rubber and/or an envelope surface of the bead core among members constituting the bead portion of the tire has a curved shape concavedly directed toward the outside of the tire at a region opposite to an inner curved surface of a slantly rising portion in a flange of the approved rim.

Pneumatic radial tires for truck and bus mounted on 15&deg; drop center rim

Pneumatic radial tires for trucks and buses mounted on 15 degree drop center rim

In a pneumatic radial tire for trucks and buses mounted on an approved 15.degree. drop center rim, an outer surface portion of a composite side-rubber and/or an envelope surface of the bead core among members constituting the bead portion of the tire has a curved shape concavedly directed toward the outside of the tire at a region opposite to an inner curved surface of a slantly rising portion in a flange of the approved rim.

Pneumatic radial tires for trucks and buses mounted on 15.degree. drop

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 includes a carcass consisting of at least one layer of metal cords substantially radially arranged, a breaker consisting of at least two layers of metal cords to form a main reinforcement with the carcass, and bead portions including hard and soft stiffeners. The carcass has a particular radial profile having a ratio of radii R/R' determined by a radius R' of a standard circle and a radius R determined by a particular definition and has a maximum distance f between an arc of the standard circle and the remaining carcass line smoothly extending from the profile curvature of the shoulder. Moreover a radial profile over a radially inner zone of the sidewall of 20-45% of the radial height SH has a curvature 1/.rho. less than 6.times.10.sup.-3 mm.sup.-1 at a location 32.5% of the radial height corresponding to a center of the profile.

Reduced rolling resistance pneumatic radial tire

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 pneumatic radial tire is adapted to improve or reduce the rolling resistance and simultaneously to improve the steering stability and riding comfortability against vibration during running without adversely affecting the wet performance and durability by making higher the carcass maximum width position and the carcass curvature reverse position, or enlarging the curvature of the carcass in the radially outer zone of the carcass maximum width position and simultaneously the carcass curvature reverse extent in the radially inner zone of the sidewalls so as to intentionally deviate from the naturally equilibrated configuration. A method of manufacturing a reduced rolling resistance pneumatic radial tire uses a mold for vulcanizing and forming the tire therein, which mold has a particular shape of cavity having a foot width 20-50% wider than a rim width and diverging progressively from shoulder corresponding portions to the wider foot portion of the cavity.

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Kodaira, Japan

Kenshiro Kato