Bridgestone Tire Company Limited

Hiroyoshi Takigawa

Hiroshi Ogawa

Nobuhiro Miyamura

Shinichiro Ohkuni

Mitsuhisa Yahagi

Hiroshi Kojima

Toshiro Tezuka

Hikaru Tansei

Shigeo Watanabe

Iwao Arimura

Shigeta Aoki

Makoto Tanaka

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 heavy duty pneumatic tire includes a tread surface divided along circumferential directions by at least two zigzag tread grooves to form a plurality of circumferential zigzag ribs whose at least one side edge is formed with a plurality of narrow cuts opening into the tread grooves and substantially in parallel with an axial direction of the tire. According to the invention, lengths and/or depths of the narrow cuts are gradually reduced from the cuts in the extending corners to the cuts in the retracting corners of the ribs, or the narrow cuts are inclined relative to radial surfaces of the tire passing through openings of the cuts to make angles with their radial surfaces, the angles being progressively larger as the cuts are nearer the extending corners to mitigate railway wear of the tire without sacrificing other wear-resistant properties.

Heavy duty pneumatic tire

A heavy duty pneumatic tire having a tread provided on its outer surface with a plurality of circumferential grooves is disclosed. At least one of the circumferential grooves is opened on the tread surface at an open groove width corresponding to 2-8% of tread transverse width, has a groove bottom width substantially equal to the open groove width, and is provided on its groove bottom with plural protrusions separated from the opposed groove walls and at an interval between the adjoining protrusions in the circumferential direction of the groove.

Tread with spaced projections in stone ejecting groove

A heavy duty pneumatic tire includes a tread in a crown of a tire body reinforced by a toroidal carcass extending between a pair of annular bead cores. The tread is formed with a pair of main wide grooves circumferentially spaced apart at least one half of a tread width of the tire on both sides of a central circumferential line and a wide subgroove extending along the central circumferential line and in parallel with the main wide grooves to form first ribs bounded by the wide subgroove and the main wide grooves and second ribs bounded by the main grooves and tread edges. Each first rib is formed with a narrow groove extending circumferentially to divide the first rib into two parts. The tire according to the invention is made superior in antiskid characteristic on wet roads by improving the drainage without sacrificing the wear resistance of the tire.

Heavy duty pneumatic tire tread

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

Vehicle tire

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 pneumatic tire for a heavy duty vehicle including a tread surface divided along circumferential directions by at least two tread zigzag grooves to form a plurality of circumferential zigzag ribs comprises stress releasing apertures formed at least in zones of the circumferential ribs which are within distances approximately 30% of widths of the circumferential ribs from the side of the ribs to mitigate stress concentrations in corners of the ribs extending in the tread grooves by reducing rigidities of the corners for preventing railway wear which would otherwise occur in the tire of this kind.

Pneumatic tire for a heavy duty vehicle

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 tire is disclosed. This tire has a tread pattern comprising projections arranged independently and spaced apart from each other in the circumferential direction of the tire and transverse grooves for separating the projections one from the other. The projection is provided with a buttress nestling from the bottom of the transverse groove along the groove wall thereof and being partly united with the groove wall. The buttress extends toward the direction of the transverse groove at a height lower than the surface level of the projection and is arranged so as to produce a narrow gap between the opposed adjacent buttresses or between the buttress and the opposite projection.

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.

Heavy duty pneumatic radial tire

A heavy duty pneumatic radial tire is disclosed. This tire has a tread pattern formed in a tread divided into zigzag circumferential ribs by at least two zigzag main grooves. The tread includes a stress-mitigating rib arranged at least near the top of the convex part of the circumferential rib and parallel to the edge line of the circumferential rib through substantially an isolation groove.

Heavy duty pneumatic radial tire with stress mitigating rib

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 flap for radial tires which is improved over a conventional flap construction is disclosed. The flap features and employs the following constructional relation between an annular wing portion of the flap and a standard wheel rim. ##EQU1## In one preferable embodiment, ##EQU2## WHERE HW IS A HEIGHT OF THE PERIPHERAL EDGE OF THE ANNULAR WING PORTION OF THE FLAP, HF IS A HEIGHT OF THE FLANGE OF THE STANDARD WHEEL RIM, AND LW IS A PERIPHERAL LENGTH OF THE ANNULAR WING PORTION OF THE FLAP PER SE FROM ITS BOTTOM TO ITS PERIPHERAL EDGE.

Growing community of inventors

Kodaira, Japan

Hiroyoshi Takigawa