Bridgestone Corporation

Yusuke Yoshikawa

Takashi Ono

Makoto Tsuruta

Hiroshi Nakata

Takashi Oono

Yasutaka Suda

Shinya Yamamoto

The present invention provides a heavy duty tire, comprising: a carcass; a belt constituted of a circumferential belt including at least one circumferential belt layer and a slant belt including at least one slanted belt layer, each belt layer being made of cords coated with belt coating rubber; and a cushion rubber provided on the outer side in the tire width direction of the belt layers, characterized in that: the cushion rubber has a belt adjacent portion adjacent to the belt and a main body portion adjacent to the belt adjacent portion; and provided that E1', E2&#x2032; and E3&#x2032; represent storage modulus values of the belt adjacent portion of the cushion rubber, the main body portion of the cushion rubber, and the belt coating rubber, respectively, E1&#x2032;, E2&#x2032; and E3&#x2032; satisfy relationship E2&#x2032;&#x3c;E1&#x2032;&#x2266;E3&#x2032;.

Heavy duty tire

A pneumatic radial tire including a carcass; two belt reinforcing layers; and a belt formed by two belt layers. A width of a belt cord intersecting region defined by the two belt layers is set in the range of 65 to 90% of the tire width-W, the maximum width of the belt reinforcing layer is set in the range of 60 to 85% of the tire width. Also, a belt radius ratio, which is a ratio of difference between the radius of the belt at the tire equatorial plane and the radius of the belt at a belt side end position thereof measured from the tire axis in a state where the tire is inflated at the standard inner pressure, with respect to a belt half width, is not larger than 0.06.

Pneumatic radial tire

The present invention provides a pneumatic tire having a carcass, at least one circumferential belt layerprovided on the outer side in the tire radial direction of the carcass, and plural intersecting belt layersprovided on the outer side in the tire radial direction of the circumferential belt layer, at least one of the plural intersecting belt layers having wider belt width in the tire widthwise direction than the circumferential belt layer, comprising: at least one layer of end-portion circumferential beltprovided in respective tire widthwise tread end regions on the outer side of the carcassand on the inner side of the circumferential belt layerin the tire radial direction; and at least one layer of slant beltprovided in the tire widthwise tread central region on the outer side of the carcassand on the inner side of the circumferential belt layerin the tire radial direction.

Pneumatic tire

The present invention relates to a method of forming at least one circumferential belt layer of a pneumatic tire comprising: winding the strip for a half length of an outer circumferential length of the crown portion of the carcass along the tire equatorial plane from a widthwise inner side of the belt end region; winding the strip for the remaining half length while shifting the strip for the width of the strip from a widthwise inner to outer side; winding the strip for the outer circumferential length of the crown portion of the carcass along the tire equatorial plane; winding the strip for the half length of the outer circumferential length of the crown portion of the carcass while shifting the strip for the width of the strip from the widthwise outer to inner side; and winding the strip for the remaining half length along the tire equatorial plane.

Pneumatic tire and method of forming circumferential belt layer of the same

The present invention provides a tire with a belt having relatively high durability by improving fatigue resistance of cords at end portions of a circumferential belt layer, in particular, and especially proposes a radial tire for heavy load, having a relatively small aspect ratio. For this purpose, the present invention provides a tire having a carcass as a skeleton provided in a toroidal shape over a pair of bead portions, a belt disposed on the outer side in the radial direction of the carcass, and a tread disposed on the outer side in the radial direction of the belt, the belt including: at least one layer of circumferential belt layer disposed on the outer side in the radial direction of a crown portion of the carcass and formed of a number of cords extending along the equatorial plane of the tire and coating rubber thereon; and at least two layers of slant belt layers disposed on the circumferential belt layer and each formed of a number of cords extending in a direction inclined with respect to the equatorial plane O of the tire and coating rubber thereon, characterized in that: a width of the circumferential belt layer is no less than 60% of the total width of the tire; a width of at least one of the slant belt layers is wider than the width of the circumferential belt layer; and modulus of elasticity of first cords disposed on an end portion side in the widthwise direction of the circumferential belt layer is lower than modulus of elasticity of second cords disposed on the inner side in the widthwise direction of the first cords.

Growing community of inventors

Kodaira, Japan

Yusuke Yoshikawa