Bridgestone Tire Company Limited

Toshiro Tezuka

Masaru Abe

Yasuo Suzuki

Isao Miyoshi

Toshio Yoshimoto

Akira Tamura

Osamu Inoue

Hiroyoshi Takigawa

Shigeru Sugihara

Minoru Nakano

A pneumatic tire for off-road vehicles, comprising a carcass body containing organic fiber cords and a breaker composed of at least one rubberized layer each containing reinforcing elements embedded therein and having an overall cut resistant property for all types of cuts together with an excellent separation resistant property and high abrasion resistant property is disclosed. The reinforcing element is composed of a bundle formed by merely assembling helically formed filaments together without twisting. The reinforcing element is formed of a material having a tensile strength of at least 140 Kg/mm.sup.2 and an elongation at breaking strength which is 0.15 to 1.7 times that of the organic fiber cord of the carcass body.

Pneumatic tires for off-road vehicles

A pneumatic tire for off-road vehicles comprising a reinforcing element composed of helically formed filaments and having an excellent side-cut resistant property is disclosed. The tire is provided at its side portion with a side portion reinforcing layer composed of at least one rubberized layer containing a reinforcing element embedded therein and formed of a helically formed filament or a bundle of at least two helically formed filaments assembled together without twisting at random. The filament is formed of a material having a tensile breaking strength of at least 140 kg/mm.sup.2. The reinforcing filament has an elongation at tensile breaking strength which is 0.15 to 1.7 times that of organic cord of a ply of a carcass body. The rubberized layer containing said reinforcing element embedded therein as a whole is extensible.

Pneumatic tire for off-road vehicles

A pneumatic radial tire having an excellent side-cut resistant property is disclosed. The radial tire comprises at least one extensible and compressible rubberized side portion reinforcing layer arranged at that area of a side portion of the tire which is inclusive of at least maximum cross-section position of the carcass and each containing a reinforcing element embedded therein and composed of helically formed filaments or at least 2 bundles each formed by merely assembling together the helically formed filaments without twisting at random. The helically formed filament is formed of a material having a tensile breaking strength of at least 140 kg/mm.sup.2. The reinforcing element has an elongation at tensile breaking strength which is at least 1.2 times larger than that of a metal cord of a radial carcass.

Pneumatic radial tire having an excellent side-cut resistant property

A tread reinforcing construction of a pneumatic radial tire for heavy-load vehicles is disclosed. The tread reinforcing construction comprises a combination of a rubberized belt superimposed about a rubberized carcass ply and at least one additional rubberized reinforcing layer interposed between the belt and a tread rubber. The additional rubberized reinforcing layer is composed of a reinforcing element embedded therein and formed of a helically formed filament or a bundle of at least two helically formed filaments assembled together without twisting at random.

Tread reinforcing construction of pneumatic radial tire for heavy-load

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.

Heavy duty pneumatic tire

An improved belt construction for a radial or semi-radial tire comprising a reinforcing belt layer including helically formed filaments is disclosed. Between main belt layers is interposed an intermediate reinforcing layer composed of a reinforcing element formed of helically formed filaments each having a tensile breaking strength of at least 140 kg/mm.sup.2 and elongation at tensile breaking strength of at least 1.2 times the smallest elongation at tensile breaking strength of the cords of the main belt layers. The intermediate reinforcing layer as a whole is extensible and compressible.

Pneumatic radial tire

A pneumatic radial tire comprising a carcass, and a belt interposed between a tread and the carcass composed of at least two main cord layers whose cords are formed of an inextensible material such as a steel cord is disclosed. The tire further comprises at least one rubberized reinforcing layer interposed between the belt and the carcass and containing reinforcing elements. The reinforcing element is formed of a helically formed filament or a bundle of a plurality of helically formed filaments. The filament has a tensile breaking strength of at least 140 kg/mm.sup.2 and elongation at tensile breaking strength which is at least 1.2 times the smallest elongation at tensile breaking strength of the main cord layers of the belt. The rubberized reinforcing layer as a whole is extensible and compressible.

Vehicle tire

A radial tire for heavy load vehicles such as light trucks, trucks, busses, super-large type construction vehicles, etc. is disclosed. The radial tire comprises a carcass ply composed of a steel cord ply and wound around a bead core from the inside toward the outside thereof to form a turn-up portion. The upper end of the turn-up portion is upwardly extended to a position located between a point passing over the maximum width point of the carcass ply expanded by applying an internal pressure to the tire and a point where a normal drawn perpendicular from a hump to the carcass ply crosses with the carcass ply. The turn-up portion of the carcass ply is separated from the carcass ply by means of a soft rubber layer composed of rubber having a Shore A hardness which is smaller than a Shore A hardness of a coating rubber of the carcass ply and a 300% modulus of elasticity which is 50% to 85% of a 300% modulus of elasticity of the coating rubber of the carcass ply.

Radial tire for heavy load vehicles

A pneumatic tire for off-road vehicles comprising a multi-layered carcass and a breaker superimposed about the carcass. The carcass is composed of rubberized ply layers each containing cords formed of organic fiber and inclined at an angle of 23.degree. to 45.degree. with respect to the equatorial line of the tire. The cords of approximately one-half of the carcass plies extend in an opposite direction to the cords associated with the remaining plies. The breaker is composed of at least one rubberized layer each containing reinforcing elements formed of a plurality of filaments whose material having a tensile strength of at least 140 Kg/mm.sup.2, the reinforcing element being inclined at an angle which is not larger than a selected angle of the carcass cord by at least 5.degree. and not smaller than the selected angle of the carcass cord by at least 15.degree.. At least one rubberized layer of the breaker disposed near the tread is extended over a width of 40 to 60% of the tread width.

Pneumatic tires suitable for off-road vehicles

A pneumatic tire for off-road vehicles, which is highly durable under heavy load conditions is disclosed. The tire makes use as its breaker of a reinforcing element formed of material having a high cut resistant property such as steel or glass. The least possible number of those plies of a plurality of rubberized ply layers of a carcass body which extend from a crown portion of the tire through both side portions up to both bead members and which can substantially withstand internal pressure applied to the tire and external force subjected thereto is determined on the basis of a fundamental safety factor .xi. and which lies within a range of a correction safety factor .eta. which depends on the use and type of the tire and the depth of tread groove.

This invention relates to an improvement in a pneumatic tire for construction vehicles. The improved tire makes use of a steel cord breaker, but can prevent mechanical and thermal separations in the tire. Breaker rubberized cords are designed to have a gap ratio given by ##EQU1## preferably 0.72 to 0.80, for the purpose of restraining the mechanical separation, where D is a distance between centers of two adjacent cords and d is a diameter of the cord. A tread rubber layer is designed to have a ratio R of a skid base S to a tire section height H given by ##EQU2## FOR THE PURPOSE OF RESTRAINING THE THERMAL SEPARATION.

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Higashimurayama, Japan

Toshiro Tezuka