Abstract: There is provided a tire-rim assembly capable of stably running over a distance required even in the dropping of the tire internal pressure after the injuring of the tire without sacrificing rolling resistance and ride comfort in the usual running before the injuring of the tire, wherein a great number of substantially sphere-shaped particles each consisting of a continuous phase of a resin and a closed cell(s) and having a mean bulk specific gravity of not more than 0.1 are disposed in an interior defined by assembling a hollow doughnut-shaped tire onto an approved rim, and a pressure at 25° C. in the interior of the tire is not less than 150 kPa as an absolute pressure.

Abstract: A rubber composition includes a rubber component, a polyethylene short fiber, and a blowing agent. The rubber component has a polybutadiene and at least one natural rubber or synthetic diene rubber. The polybutadiene has a weight-average molecular weight of 5,000 to 30,000 obtained as a weight-average molecular weight corresponding to polystyrene and further has a content of a cis-1,4 structure of 60 to 98%. The rubber component is 6% by weight or more polybutadiene. The short fiber has an average length of 10 mm or shorter. A pneumatic tire includes the rubber composition and exhibits excellent braking ability on ice, excellent braking ability on wet road surfaces, and improved driving stability in the early driving period. The pneumatic tire exhibits remarkable improvement in braking ability on ice even after a base rubber is exposed by abrasion of a tread rubber.

Abstract: A tire having a portion formed of a rubber composition which comprises a high-molecular-weight polymer component which contains bound styrene in an amount not greater than 30% by weight, is a styrene-butadiene copolymer or a conjugated diene polymer such as polybutadiene, and has a weight-average molecular weight of at least 30.times.10.sup.4 ; and a low-molecular-weight polymer component which contains bound styrene in an amount not greater than 30% by weight, is a styrene-butadiene copolymer or a conjugated diene polymer such as polybutadiene, and has a weight-average molecular weight of from 0.2.times.10.sup.4 to 8.times.10.sup.4. The rubber composition contains 30 parts by weight of the low-molecular-weight polymer component relative to 100 parts by weight of the high-molecular-weight polymer component. The ratio between the amount of bound styrene and the vinyl linkage content falls within specific ranges.