Toyo Tire Rubber Co., Ltd.

The Toyo Rubber Industry Co., Ltd.

Keijiro Oda

Katsuji Kishida

Masakazu Onishi

Tetsuto Ueno

Masanori Kan

Yukio Komai

Takuya Okazaki

Hiroshi Takino

Eiji Ida

Yusho Fuchikami

Toyohiko Asada

Masahide Nishihata

Yukitoshi Morishita

Masakazu Oonishi

A tire having superior cut resistance and less belt separation comprising a tread with steel cord belts in which a center rubber for middle part of the tread and a side rubber for both sides thereof are respectively formed of different rubber compositions, and in which at least an inner portion of the center rubber is composed of a rubber composition of superior cut resistance wherein either a natural rubber of a SBR blended natural rubber is compounded with carbon black of large iodine absorption number, silica and silane coupling agent expressed by a formula of (OR).sub.3 SiCnH.sub.2 nSmCnH.sub.2 nSi(OR).sub.3 or (OR).sub.3 SiCnH.sub.2 nX, while the side rubber is composed of a rubber composition having small heat build up.

Tire of superior cut resistance

The invention relates to a radial tire in which each sidewall covering and protecting the side face of the carcass is composed of a plurality of layers differing in rubber composition. In the radial tire according to the invention, the sidewall has a three-layer structure consisting of an adjesive layer adjacent to the carcass, an inner layer disposed outwardly thereon and an outer layer disposed further outwardly thereon. The rubber components in the rubber compositions respectively constituting the three layers differ in proportions of the rubber having as low degree of unsaturation and the rubber having a high degree of unsaturation and the high-unsaturation rubber content decreases in the order of adhesive layer, inner layer and out layer. While retaining the endurance characteristics and ozone resistance of the conventional tires, the radial tire according to the invention is improved in that its good appearance can be prevented from being spoiled by staining or discoloration of its side portions. In spite of the use of rubbers having a low degree of unsaturation, the invention provides a radial tire having sidewalls excellent in adhesiveness to the carcass and other portions made of a diene rubber composition.

Radial tire with a sidewall having a three-layer structure

A radial tire improved in steering stability, durability and appearance comprising a nylon cord of high modulus and excellent dimensional stability obtained by impregnating a nylon cord substantially composed of polytetramethyleneadipamide with an adhesive and heat setting the nylon cord under a stretch state.

Radial tire

A rubber composition for treads characterized in that the composition comprises 100 parts by weight of a rubber component and 50 to 100 parts by weight of carbon black admixed therewith, the rubber component comprising 10 to 50 parts by weight of a solution-polymerized star styrene-butadiene rubber (I) having specific styrene content, vinyl content of the butadiene portion and at least 40% in the efficiency of coupling with a tin halide, 20 to 70 parts by weight of a solution-polymerized straight-chain styrene-butadiene rubber (II) having specific styrene content and vinyl content of the butadiene portion and 10 to 50 parts by weight of natural rubber or isoprene rubber (III), the carbon black being in the range of 75 to 105 in nitrogen adsorption specific surface area (N.sub.2 SA), at least 15 in the difference between N.sub.2 SA and the iodine adsorption number (IA) thereof and 0 to 5 in the difference between N.sub.2 SA and the cetylitrimethylammonium bromide adsorption specific surface area (CTAB) thereof, the composition being -50.degree. to -30.degree. C. in the peak temperature of loss tangent, tan .delta..

Rubber composition for treads

A pneumatic radial tire having highly durable bead structure is disclosed. One or more carcass ply layers of steel cords are turned up around a bead core from the inside to the outside. A reinforcing strip of steel cords is positioned outwardly adjacent to the turn-ups of carcass plies. A bead filler of approximately triangular sectional shape is disposed at the region enclosed by the carcass plies, the turn-ups of the carcass plies and the reinforcing strip of steel cords. The bead filler comprises high hardness rubber stock and medium hardness rubber stock. A cap of organic textile cord fabric covers an upper end of the reinforcing strip of steel cords. A fin-shaped rubber buffer having a hardness lower than that of the medium hardness rubber stock by 3.degree. to 20.degree. is disposed radially outwardly of the capped end and axially outwardly adjacent to the medium hardness rubber stock. A reinforcing strip of organic textile cords may be further disposed outwardly adjacent to the reinforcing strip of steel cords.

Pneumatic radial tire having durable bead structure

A pneumatic radial tire having highly durable bead structure is disclosed. One or more carcass ply layers of steel cords are turned up around a bead core from the inside to the outside. A reinforcing strip of steel cords is positioned outwardly adjacent to and without extending radially outwardly beyond the turn-ups of carcass plies. A bead filler of approximately triangular sectional shape is disposed at the region enclosed by the carcass plies and the turn-ups of the carcass plies. The bead filler comprises high hardness rubber stock and medium hardness rubber stock. A cap of organic textile cord fabric covers an upper end of the carcass plies. A fin-shaped rubber buffer having a hardness lower than that of the medium hardness rubber stock by 3.degree. to 20.degree. is disposed radially outwardly of the capped end and axially outwardly adjacent to the medium hardness rubber stock. A reinforcing strip of organic textile cords may be further disposed outwardly adjacent to the reinforcing strip of steel cords.

Pneumatic radial tire having highly durable bead structure

A pneumatic radial tire having highly durable bead structure is disclosed. A carcass ply layer of organic textile cords is turned up around a bead core from the inside to the outside. A reinforcing strip of steel cords is positioned outwardly adjacent to the turn-ups of carcass plies. An organic textile cord fabric is disposed outwardly adjacent to the reinforcing strip of steel cords. A bead filler of approximately triangular sectional shape is disposed at the region enclosed by the carcass plies, the turn-ups of the carcass plies and the reinforcing strip of steel cords. The bead filler comprises high hardness rubber stock and medium hardness rubber stock. A cap of organic textile cord fabric covers an upper end of the reinforcing strip of steel cords. A fin-shaped rubber buffer having a hardness lower than that of the medium hardness rubber stock by 3.degree. to 20.degree. is disposed radially outwardly of the capped end and axially outwardly adjacent to the medium hardness rubber stock.

A pneumatic radial-ply tire having a tread constructed of at least two kinds of rubber which is capable of attaining both braking performance and rolling resistance. The tread portion is constructed so that the tread center zone is comprised of a rubber having a low hysteresis loss and the tread side zones adjacent to the center zone on both sides thereof or the outer layers of them are each comprised of a rubber having a high hysteresis loss; the tread center zone and the tread side zones are disposed in parallel to each other in the circumferential direction or the tread side zones are each disposed adjoining to the tread center zone and in a superposing manner.

Growing community of inventors

Kawanishi, Japan

Keijiro Oda