The Yokohama Rubber Co., Ltd.

Hiroaki Matsuzaki

Akinori Tokieda

Kazuyoshi Saneto

Kunihiko Kakigi

A run-flat pneumatic radial tire having an aspect ratio of up to 50%, which includes a reinforcing liner layer made of a rubber having a complex modulus at 20.degree. C. E*.sub.20, a ratio of a complex modulus at 100.degree. C. to the complex modulus at 20.degree. C., a 100% modulus and a loss tangent (tan .delta.) at 100.degree. C. which satisfy certain specified numeric values. The liner has a crescent sectional shape and is disposed in sidewall portions of a carcass layer with its end portions overlapping the end portions of a belt layer and a bead filler having a specified hardness and height h from a wheel rim base. The carcass layer consists of an inner carcass layer turned up around the bead core from inside to outside the tire so that its end portion is positioned at a position higher than the height h of the bead filler and an outer carcass layer having an end portion disposed axially outward of the bead core.

Run-flat pneumatic radial tire

A run flat pneumatic radial tire having a flatness of 50% or less, comprising a reinforcing liner layer comprised of a high-hardness rubber having a crescent cross section disposed on the inside of a side wall portion and an inner liner layer comprising a rubber composition mainly composed of a butyl rubber provided all over the internal surface of the tire, wherein the inside of the inner liner layer in at least a region covering said reinforcing liner layer is covered with a rubber layer comprising a rubber composition mainly composed of a diene rubber having a polybutadiene rubber content of 50% by weight or more based on the rubber component.

Run flat pneumatic radial tire

A run-flat pneumatic radial tire having an aspect ratio of up to 50%, which includes a reinforcing liner layer mode of a rubber having a complex modulus at 20.degree. C. E*.sub.20, a ratio of a complex modulus at 100.degree. C. to the complex modulus at 20.degree. C., a 100% modulus and a loss tangent (tan .delta.) at 100.degree. C. which satisfy certain specified numeric values. The liner has a crescent sectional shape and is disposed in sidewall portions of a carcass layer with its end portions overlapping the end portions of a belt layer and a bead filler having a specified hardness and height h from a wheel rim base. The carcass layer consists of an inner carcass layer turned up around the bead core from inside to outside the tire so that its end portion is positioned at a position higher than the height h of the bead filler and an outer carcass layer having an end portion disposed axially outward of the bead core.

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Kawasaki, Japan

Hiroaki Matsuzaki