Bridgestone Tire Company Limited

Bridgestone Corporation

Munetoshi Shimotake

Yoshihiro Sakai

Tamio Araki

Koichi Kojima

Toshio Kita

Tsuguyoshi Yamada

Ryosaku Tanaka

Hiroshi Ueda

Yasuyosi Kawaguchi

Fujio Yamamoto

A radial tire having excellent cornering stability and high-speed durability is disclosed. The tire has a belt composed of a first structural body, which consists of a single rubberized cord layer containing cords of twisted metal wires and is folded at both lengthwise end portions, and a second structural body consisting of at least one rubberized cord layer containing unextensible cords, wherein the cord of twisted metal wires used in the first structural body has a specifically limited twisting construction and a specifically limited elongation.

Radial tire having an improving durability

A light tire body using thick cords is disclosed. The tire body comprises a bias-structured carcass composed of rubberized plies each including thick organic fiber cords. The rubber between the carcass plies has a thickness corresponding to hm/ho.ltoreq.0.5 where hm is an average rubber gauge between the plies at a center position in a widthwise direction of tire and ho is a diameter of the thick cord, and is prepared from a compounding recipe of at least one rubber ingredient selected from natural rubber and diene rubbers, a softener, an organic vulcanization accelerator and sulfur as well as at least 30 wt.% of carbon black having an average iodine adsorption value of 40-90 mg/g and an average DBP absorption value of 60-140 ml/100 g, and has a dynamic modulus of elasticity E' at 100.degree. C. under 2% elongation given by E'.gtoreq.6.0.times.10.sup.7 dyne/cm.sup.2, a dynamic loss angle tan.delta. given by tan.delta..ltoreq.0.095 and a tensile strength of not less than 100 kg/cm.sup.2 as properties after vulcanization.

Light tire bodies using thick cords

A thick-cord lightweight tire body having an improved fatigue life is disclosed. The tire body comprises a bias-structured carcass composed of rubberized plies each including thick organic fiber cords and rubber interposed between the carcass plies. The rubber has a thickness corresponding to hm/ho.ltoreq.0.5, where hm is an average rubber gauge between the plies at a center position in a widthwise direction of tire and, ho is a diameter of the thick cord, and is a rubber composition consisting essentially of 100 parts by weight of a rubber component and 50-70 parts by weight of carbon black. The rubber component is a mixture of 60-95 parts by weight of a rubber and 5-40 parts by weight of a liquid polymer having a viscosity-average molecular weight of 3.times.10.sup.4 -10.times.10.sup.4. The rubber composition has a dynamic modulus of elasticity E' at 100.degree. C. under 2% elongation given by E'.gtoreq.6.0.times.10.sup.7 dyne/cm.sup.2, a dynamic loss angle tan .delta. given by tan .delta..ltoreq.0.095 and a tensile strength of not less than 100 kg/cm.sup.2 as properties after vulcanization.

Thick-cord lightweight tire body having an improved fatigue life

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Kodaira, Japan

Munetoshi Shimotake