Bridgestone Tire Company Limited

Bridgestone Corporation

City of Sapporo

Bridgestone Corporation 10-1

Hiroshi Ogawa

Hiroyoshi Takigawa

Kenichi Motomura

Shinichiro Ohkuni

Hikaru Tansei

Mitsuhisa Yahagi

Nobuhiro Miyamura

Yukimasa Yamada

Mamoru Mamada

Shigeta Aoki

Shigeo Watanabe

Masaharu Sumiuchi

Hironori Hirano

Tatsuo Arai

Hirozi Yamada

Makoto Yoshioka

Akira Yamamoto

Takeshi Yonezawa

Satoru Aono

Noriyuki Hagita

Seiichiro Nishiide

Masato Sueyasu

A method of bending back a tire component, comprising a step in which the diameters of a pair of cylindrical bodies, whose diameters can be increased and decreased, are decreased to a minimum value to hold beads by the bodies, respectively, and the beads are set in prescribed positions on the component wound on a forming drum; a step in which the diameters of the bodies are increased to an intermediate value and the bladders of the drum are inflated so that the component is pinch-held at both side edges thereof by the bladders and the bodies; a step in which the bodies are moved to positions located nearly outside the beads in the radial directions of the bodies, so that both the side edges of the component are moved outward in the radial directions of the bodies as the component remains in pressure contact with the beads near the side edges; and a step in which the diameters of the bodies are increased to a maximum value and the bodies are thereafter moved toward the longitudinally central portion of the drum so that the component is bent back at both the side edges thereof around the beads by the bodies, the bladders and the body of the drum.

Method of bending back tire component and apparatus for said bending-back

To maintain excellent antiwet skidding performance and good tire external appearance until a radial tire for heavy-duty road vehicles serves its time, a plurality of narrow grooves (40) are formed along at least longitudinal direction of each of plural platforms arranged at intervals in circumferential direction of each of land portions formed between two main circumferential grooves, in order to separate the platform from the tire land portion. This is because the narrow grooves serve to decrease the rigidity of the platforms and therfore to allow the platforms to be more slidably movable relative to the ground to increase abrasion rate on the platform surface, thus maintaining a height difference between the tire land portions and the platforms.

Radial tire tread for heavy-duty road vehicles having platform depth

A pneumatic tire comprising a tread divided into at least three ribs by at least two main wide grooves extending substantially in a circumferential direction of the tire, wherein a shoulder rib arranged at an outermost end portion of the tread is divided in an axial direction parallel to an axis of rotation of the tire into at least two shoulder rib portions; and between two adjacent shoulder rib portions of said at least two shoulder rib portions, an outer surface of an outer shoulder rib portion is radially inwardly disposed with respect to an extension line of an outer surface of an inner shoulder rib portion arranged inwardly of the outer rib portion. A plurality of sipes may be formed in the vicinity of an outer end of at least one shoulder rib portion other than an outermost shoulder rib portion. Further, a plurality of sipes are formed in the vicinities of outer ends of at least two rib portions other than an outermost rib portion, the quantity of siping being gradually reduced in the axial direction.

Pneumatic tire tread with divided shoulder

A pneumatic tire comprising a tread divided into at least three ribs by at least two main wide grooves substantially extending in a circumferential direction of the tire, wherein a shoulder rib of the ribs arranged at an outermost end portion of the tread is divided in an axial direction parallel to an axis of rotation of the tire into at least two rib portions; and between two adjacent rib portions of the rib portions, an inner end of an outer surface of an outer rib portion is connected through an outer surface of a circumferentially extending sloped portion to an outer end of an outer surface of an inner rib portion so that the outer end of the outer surface of the outer rib portion is lower than the inner end of the outer surface of the inner rib portion.

Pneumatic tire tread with recessed shoulder portion

A novel tread pattern is disclosed, which can give high performances on wet road at both the straight running and the cornering under a low load, particularly no load, to a heavy duty pneumatic radial tire without sacrificing the performances on wet road under normal load. The tread pattern comprises at least 4 lands defined by at least 3 main grooves, wherein a pair of first group lands arranged on the outermost side regions of the tread have substantially continuous along the the circumferential direction of the tread and the remaining lands located between the first group lands have notches arranged thereon in their lateral direction.

Heavy duty pneumatic radial tire

A heavy duty radial tire having a tread of a double zigzag pattern, wherein the main groove is formed into a zigzag and further the ridge of a rib adjacent to the zigzag main groove is formed into a zigzag, whose pitch and amplitude are considerably smaller than those of the zigzag main groove, has a high irregular wear resistance without deteriorating the wet performance of the tire.

Heavy duty radial tire

A large-sized pneumatic radial tire is disclosed. The tire comprises a tread including grooves, a belt composed of a plurality of rubberized layers each containing steel cords, and a carcass of a substantially radial construction. The tread includes two half regions divided with respect to a crown center, one a region in a direction of plysteer due to the tire construction and the ground contact reaction force acting on steel cords of at least one rubberized layer disposed near the tread, and the other being a region opposite to the direction of plysteer. A row of small holes are formed in an island part along its edge near the kicking-out side of the groove in the region opposite to the direction of plysteer.

Large-sized pneumatic radial tires

A pneumatic tire for heavy load vehicles such as trucks and buses comprising a tread composed of a flat main region and an inclined region located at both side edges of the flat main region and including a number of notches spaced apart from each other and arranged substantially transversely to the circumferential direction of the tire.

Pneumatic tire for heavy load vehicles

A heavy duty pneumatic radial tire exhibiting less railway wear is disclosed. This tire has a tread pattern formed in a tread divided into a plurality of circumferential ribs by at least two zigzag grooves. Each of these zigzag grooves has a width, amplitude and pitch of 4.5 to 7.5%, 0.5 to 2.0% and 2.0 to 7.0%, respectively, based on a width of the tread.

Heavy duty pneumatic radial tire exhibiting less railway wear

A radial tire for heavy load vehicles comprising a tread portion having an outer contour composed of a relatively transversely flat main region and a conical region located at both end edges of the main region. A number of thin incisions extend across the conical region having inner ends not reaching to the inside of the main region.

Radial tire for heavy load vehicles

A heavy duty pneumatic radial tire comprises a tread continuous at its round-shaped shoulders with sidewalls and formed with a plurality of main tread grooves extending circumferentially thereof. The tread is formed with a circumferentially extending narrow groove in zigzag in each end zone of contact surfaces of the shoulders with a road surface under a standard load. The zigzag grooves have a width of 15-30% of that of the main tread grooves, an amplitude of 0.5-2.0% of the tread width and a pitch of 2.0-7.0% of the tread width. Each of the shoulders is formed in its side surface with a series of intermittent circumferential caved portions, such that a distance in an axial direction of the tire between the deepest bottoms of the caved portions is 105-110% of the tread width and the deepest bottoms are located in a circle having a diameter less than that of a circle passing through the bottoms of the main tread grooves. With the arrangement, the tire according to the invention does not cause any irregular wear at the shoulders and can reduce and prevent the railway wear and growth thereof toward the center of the tread, so that the wear-resistance of the tire is remarkably improved.

A large-sized pneumatic radial tire is disclosed. This tire comprises a tread including grooves, a belt composed of a plurality of rubberized layers each containing steel cords, and a carcass of a radial or semiradial construction. The tread includes two half regions divided with respect to a crown center, one of which being a region in a direction of plysteer due to the tire construction and the ground contact reaction force acting to steel cords of at least one rubberized layer disposed near the tread and the other being a region opposite to the direction of plysteer. Reinforcements are provided on walls of tread grooves at kicking-out side of the region opposite to the direction of plysteer.

Large-sized pneumatic radial 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.

A testing machine for a tire on an imitation road in which a tire to be tested is urged against a crawler with the aid of a cantilever arm connected through a crosshead to a lifting and lowering disc engaged with screw threaded rods rotatably mounted in a machine frame. The crawler is composed of an endless chain and a road surface forming rods detachably mounted on the endless chain and replaceable by new rods made of different kind of material. In the crosshead are incorporated slip and camber angle setting mechanisms. Provision is made of load cells such as a strain gauge operatively connected to a tire supporting shaft, driving and driven shafts of the crawler and a guide rail of the crawler and for detecting a vertical load subjected to the tire, a torque for driving the crawler under various load conditions and a transverse component of force subjected to the crawler when the tire having a given slip angle or a camber angle is urged against the crawler.

Growing community of inventors

Kodaira, Japan

Hiroshi Ogawa