Bridgestone Corporation

Shuji Ando

Yoichi Honbo

Kazuomi Kobayashi

This invention is concerned with a radial tire, particularly a heavy duty radial tire aiming at the improvement of durability, and is characterized by rendering a ratio W/Wof width Wof a belt layer located side a carcass to width Wof the remaining belt layer in small slant belt layers arranged at a width corresponding to 0.25&#x2013;0.50 times a tread width in a widthwise direction of the tire, whereby growth and progress of cracks in the vicinity of cord ends of cords used in the belt resulting in separation failure at widthwise ends of the belt are effectively prevented to overcome a weak point in the tread reinforcement of the radial tire.

Radial tire including two small slant belt layers

A heavy duty pneumatic radial tire comprises a pair of bead portions each containing a bead core, a radial carcass, a belt comprised of at least one belt layer, and a tread, in which (1) a tapering angle &thgr;,of an inner side of the bead core in the radial direction is within &plusmn;2&deg; of a tapering angle &thgr;,of a bead seat part in an approved rim, and (2) a compression ratio Ca at a widthwise inner end of the inner side of the bead core is within a range of 102-115% of a compression ratio Cb at a widthwise outer end thereof.

Heavy duty pneumatic radial tires with specified bead core compression ratio

Automobile tire

A heavy duty pneumatic radial tire has an outer profile of a tread portion in radial section of the tire having a given composite arc shape as a function of the internal structure of the tire, particularly a belt structure including at least two belt layers inclusive of main cross belt layers of steel cords.

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Kodaira, Japan

Shuji Ando