Bridgestone Tire Company Limited

Shigeo Watanabe

Toshiyuki Sogi

Shigeo Makino

Hiroshi Kojima

Toshio Hayakawa

Hidenori Takahashi

Kenichi Motomura

Hiroyoshi Takigawa

Hiroshi Ogawa

Muneyoshi Maeda

Shigeta Aoki

Hiroshi Tamura

A pneumatic radial tire having an improved bead portion reinforcing construction is disclosed. The radial tire comprises a bead portion reinforcing band disposed along the bead portion formed by folding the ply of the carcass body around the bead ring. The bead portion reinforcing band comprises at least one chipper layer. The chipper is composed of a reinforcing element embedded in rubber and formed of 1 to 50 helically formed filaments. The reinforcing element has a modulus of elasticity of 0.029.times.10.sup.4 kg/mm.sup.2 to 1.60.times.10.sup.4 kg/mm.sup.2 and is inclined at a given angle with respect to the ply cords of the carcass body so as to make the chipper as a whole extensible and rigid.

Pneumatic radial tire having an improved bead portion reinforcing

A radial tire provided with a tread pattern suitable for travel on paved roads at a high speed is disclosed. The tread pattern is of a block-rib type which is constructed to satisfy the following conditions, i.e.

Pneumatic tires for heavy vehicles

Vehicle tire

A heavy duty pneumatic radial tire having tread patterns divided into a central zone and peripheral zones by two main continuous zigzag grooves spaced apart a distance 25-38% of the overall width of the tread and having a main groove oblique or zigzag angle of 55-78.degree. relative to a radial plane of the tire. Each of the peripheral zones is divided into the form of arrow feathers by traverse grooves having walls tilted through at least 20% of the depth of the traverse groove at an angle within 20-40.degree. to a center line of the traverse groove. The ratio of total areas of the central zone to those of one of the peripheral zones is 1:1.0 to 1:1.5, and the ratio of the total areas of inner and outer peripheral blocks in the peripheral zones divided by a continuous zigzag groove substantially parallel with the main grooves is 1:1.5 to 1:2.5, thereby greatly mitigating ununiform wear at the shoulders of the tread, heal-and-tow wear between front and rear edges of blocks defined by the grooves in the pattern, and railway wear at the edges of the blocks in opposition to the grooves.

Heavy duty pneumatic radial tire

A pneumatic radial tire for heavy load vehicles comprises a carcass and a belt for reinforcement of the carcass, said belt including tension members composed of at least two rubberized metal cords crossing with each other at a cord angle of not more than 25.degree. with respect to equatorial plane of tire, in which said metal cords is coated with a rubber having a modulus of elasticity of 40-80 Kg/cm.sup.2, a distance between the cords in each tension member is widened to 0.2-0.75 d based on a diameter d of the cord, and an interlaminar cord distance D between the tension members is uniformly shortened to 0.2-0.4 d at a central region extending within 50-80% of a superposed width of the tension members.

Pneumatic radial tire for heavy load vehicles

A radial tire having a highly durable bead structure, comprising a carcass ply having a high modulus of elasticity is disclosed. The bead is constructed to satisfy the following conditions, i.e.,

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Kokubunji, Japan

Shigeo Watanabe