Bridgestone Corporation

Makoto Tsuruta

Hiroyuki Iida

Hiroshi Nakamura

Takashi Ono

Yusuke Yoshikawa

Hiroyuki Koseki

Yasuhiko Kobayashi

Hiroshi Nakata

Takashi Oono

Yuji Yamaguchi

Atsushi Yamada

Atsushi Miyasaka

Yoshihide Kohno

Masashi Yamaguchi

Yasutoshi Aoki

Takahiro Kimura

Yasutaka Suda

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 includes a run-flat tirecomprising a plurality of turbulence generation ridgeswhich extend on a surface of a tire side portionin a tire-radial direction and which are arranged at a pitch in a tire-circumferential direction and relationship Si&#x3e;So is satisfied. Si is the sum of sidewall areas of all the turbulence generation ridges located at the inner side, in the tire-radial direction, of a maximum width position of the pneumatic tire. So is the sum of sidewall areas of all the turbulence generation ridges located at the outer side, in the tire-radial direction, of the tire maximum width position.

Pneumatic tire

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.

A pneumatic tire to effectively enhance the transversal stiffness and prevented the carcass from breaking before the other reinforcement members break is provided. A tread rubber is arranged radially outwardly on the crown portion of the carcass. A belt consisting of at least one belt layer is arranged between the tread rubber and the carcass. The belt layer containing cords extending in a direction inclined from the tire's circumferential direction. At least one circumferential reinforcement layer containing meandering cords extending generally along the tire's circumferential direction in a wavy or zigzag shape is provided radially outwardly or inwardly on the belt or between the belt layers. At least one transversal reinforcement layer containing straight cords extending generally perpendicular to the tire's circumferential direction is provided on the position radially outwardly adjacent to the crown portion of the carcass.

Pneumatic tire with circumferential and transversal reinforcement layers

A belt durability is improved by effectively suppressing an interlayer separation between each widthwise outer end portion of a belt reinforcing layerand a belt layer, in which each widthwise outer endof one widest-width inner belt plyis located outward from each widthwise outer endof widest-width reinforcing pliesin the widthwise direction and hence reinforcing elements of the belt plies are not crossed with each other at the outside from the each widthwise outer endin the widthwise direction. Therefore, the each widthwise outer end portion of the inner belt plyis easily reduced in the widthwise direction, whereby shearing deformation in section to the each widthwise outer end portion of the reinforcing plyis reduced.

Pneumatic radial tire with belt reinforcing layer between carcass layer and belt layer

A pneumatic tire comprises a carcass, a belt comprised of at least two belt layers, a belt reinforcement arranged between the carcass and the belt and comprised of at least one belt reinforcing layer, and a tread rubber, in which a widthwise outer end of a widest-width belt reinforcing layer is arranged outward from a widthwise outer end of a widest-width belt layer among the belt layers, and a restraining rubber having a width of not less than 4 mm and a JIS hardness not less than a JIS hardness of a coating rubber for the widest-width belt reinforcing layer is arranged outward from the widthwise outer end of the widest-width belt reinforcing layer.

Pneumatic tires

A pneumatic radial tire comprises a radial carcass, a cross belt comprised of at least two belt layers, a belt reinforcing member arranged adjacent to the belt and comprised of at least one belt reinforcing layer containing a reinforcing element embedded therein and extending in a circumferential direction while bending in form of wave or zigzag, and a tread rubber, in which the widthwise outer end of the belt reinforcing member is located outward from the widthwise outer end of the widest-width belt layer, or a belt protection member is disposed in the neighborhood of the belt so that the widthwise outer end of the belt protection member is located outward from the widthwise outer end of the belt reinforcing member in a widthwise direction of the tire.

Pneumatic radial tires

A pneumatic radial tire includes a belt comprised of at least two rubberized steel wire element layers, in which the belt comprises an outermost slant element layer containing the steel wire elements obliquely arranged with respect to an equatorial plane of the tire and at least one circumferential element layer located inward from the outermost slant element layer in a radial direction of the tire and containing the steel wire elements arranged substantially in parallel to the equatorial plane, and a coating rubber for the steel wire element in the outermost slant element layer has a given modulus of elasticity at compression, and a sum of sectional area of the steel wire elements in the circumferential element layer per unit length is larger than a sum of sectional area of the steel wire elements in the outermost slant element layer per the same unit length.

Pneumatic radial tires with specified steel belts

A pneumatic radial tire comprises a tread portion, a pair of sidewall portions, a pair of bead portions, a carcass of at least one rubberized ply containing cords arranged in a radial direction and consisting of a main carcass body and a turnup portion. A belt is superimposed about a crown portion of the carcass, and a rubber filler is arranged between the main carcass body and the turnup portion above the bead core. The rubber filler is composed of three different rubber stocks, and a hardest rubber stock among these rubber stocks is arranged in at least an outer zone in the radial direction of the tire sandwiching a normal line drawn from the turnup end to the outer surface of the main carcass body at a cross section of the tire and perpendicular to the main carcass body. A rubber stock having a middle hardness is arranged between the outer surface of the main carcass body and the hardest rubber stock as a stress-mitigating rubber layer. A softest rubber stock is arranged along an inner surface of the turnup portion.

Pneumatic radial tires with rubber filler composed of three rubber stocks

A heavy duty pneumatic radial tire comprises a tread portion, a pair of sidewall portions, a pair of bead portions containing a pair of bead cores therein, at least one radial carcass ply, and a bead filler comprised of at least two rubber stocks, in which at least a part of an outer surface of a turnup portion of the carcass ply in axial direction of the tire is covered with a deformation-absorbing rubber layer arranged along an upper rubber stock of the bead filler and having a Shore A hardness of not more than 55.degree..

Heavy duty pneumatic radial tires with deformation-absorbing rubber

A pneumatic radial tire, particularly a large-size and low-section profile pneumatic radial tire for truck and bus includes a stiffener disposed between a main body portion and each turnup portion of a carcass and constructed with a one-piece molded body of two or more rubber compositions having different hardnesses. A rubber composition having a highest hardness is arranged near to the main body portion of the carcass as a deformation-isolating rubber member having a greatest thickness at a position separated from a perpendicular line (Lv) drawn from an end of the turnup portion toward an outer surface of the carcass main body portion in tire cross-section, at least in a side of the tread portion among both sides sandwiching the perpendicular line (Lv), and a rubber composition having a lower hardness is arranged along an inner surface of the turnup portion.

Pneumatic radial tires with one-piece molded stiffener having at least

A pneumatic radial tire comprises a pair of bead cores, at least one radial carcass ply comprised of a main body and a turnup portion, and a stiffener arranged between the main body and each turnup portion wound around each bead core, in which each stiffener is composed of first, second and third stiffener members, and a boundary surface X between the first and second stiffener members is inclined outward in the radial direction so as to approach to the main body and a boundary surface Y between the second and third stiffener members is inclined outward in the radial direction so as to separate away from the main body, and a ply end rubber member made from rubber having a hardness between the hardnesses of the first and third stiffener members is arranged on an outer end region of the turnup portion in the radial direction.

Pneumatic radial tires with stiffeners composed of three stiffener

A pneumatic tire comprising a pair of beads, and a carcass ply consisting of a main body located axially inside the beads and outer ply portions extending along the main body of the carcass ply axially outside each of the beads. A number of circumferentially spaced recesses are provided in the outer surface of the tire between a radially outer end of each of the outer ply portions and a location corresponding to a maximum width of the tire, and the recesses has a depth equal to 1/10 time to 1/2 time as large as a thickness of those portions of the tire which are provided with the recesses. The inclined angle of a base portion of each of the beads is about 15.degree. relative to the rotary axis of the tire. In the tire, 0.4P.ltoreq.W.ltoreq.0.8P and B.ltoreq.0.06D in which P, B, W and D are a circumferential pitch of the recesses, a minimum distance between the adjacent recesses, a circumferential width of each of the recesses which is obtained by deducting the minimum distance B from the pitch P, and a diameter of a rim base, respectively.

Pneumatic tires with sidewall recesses

A pneumatic tire involves a toroidal carcass ply extending between a pair of beads. The carcass ply consists of a main body located axially inside the beads and a pair of outer ply portions each extending along the main body of the carcass ply and on an axially outer side of the bead. A recess is provided on an outer surface of the tire between a radially outer end of each of the outer ply portions of the tire and the tire maximum width location such that a part of the recess is located in a zone surrounded by a curve C--C, a curve D--D, and an E-axis. The curve C--C satisfies d/s=1-0.825.times..sqroot.2.64-(h/s), and the curves C--C, and D--D, the E-axis, d, s, h are defined as follows: a widthwise center line of the main body of the carcass ply being taken as A--A; a curve passing through the radially outer end of the outer ply portion and being parallel with the curve A--A being taken as B--B; an axis lying on the curve B--B and extending from the radially outer end of the outer ply portion toward the location having maximum width being taken as an H-axis; an axis extending from the radially outer end of the outer ply portion toward an interior of the tire in a direction orthogonal to the H-axis being taken as the E-axis; a distance from an origin as measured along the E-axis extending the radially outer end of the outer ply portion toward the interior of the tire in a direction orthogonal to the H-axis being taken as d, the origin being an intersection between the E-axis and the H-axis; a distance from the radially outer end of the outer ply portion to the center line A--A as measured on the F-axis being taken as s; a distance from the origin as measured along the H-axis being taken as h; and the curve D--D being a curve extending between the curves A--A and B--B and being parallel with the center line A--A, while being spaced from the center line A--A by 1/3s.

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Akishima, Japan

Makoto Tsuruta