Abstract: A tread rubber composition of excellent hydrophobic property and water repellency suitable to a studless tire of excellent performance on ice, comprising a diene rubber comprising at least one rubber selected from the group consisting of natural rubber, isoprene and polybutadiene as a main ingredient and, based on 100 parts by weight of the diene rubber, from 10 to 40 parts by weight of a clay comprising kaolinite as a main ingredient and having an oil absorption amount of from 50 to 70 g/100 g and 0.1 to 8 parts by weight of a silane coupling agent.

Abstract: A rubber composition suitable for reinforcing beads of tires, having high hardness, high durability and high aging resistance, which comprises a rubber component containing 30 to 70% by weight of a butadiene rubber containing syndiotactic crystals, 60 to 75 parts by weight of a carbon black having a specified iodine adsorption number and a specified oil absorption, 1 to 2 parts by weight of sulfur and 2 to 4 parts by weight of a sulfenamide accelerator, respectively, per 100 parts by weight of the rubber component, wherein the total amount of sulfur and the sulfenamide accelerator is from 3 to 5 parts by weight.

Abstract: A tread rubber composition is provided which includes 100 parts by weight of a diene rubber containing as a main component thereof at least one rubber selected from the group consisting of natural rubber, polyisoprene and polybutadiene, and 30 to 90 parts by weight of a vulcanized rubber powder, wherein the vulcanized rubber powder is a powder of a rubber resulting from the vulcanization of a rubber composition including 100 parts by weight of a diene rubber containing as a main component thereof at least one rubber selected from the group consisting of natural rubber, polyisoprene and polybutadiene, and 30 to 100 parts by weight of a clay mainly composed of kaolinite. The rubber composition for tire tread assures improved braking performance with the fracture resistance thereof kept satisfactory and, hence, a tire tread made of such rubber composition makes it possible to build a studless tire exhibiting an improved gripping force.

Abstract: A pneumatic tire having a tread rubber layer disposed radially outside a carcass, a sidewall rubber layer disposed axially outside the carcass in each sidewall portion, the sidewall rubber layer softer than the tread rubber layer, a protective rubber layer disposed on the outer surface of the sidewall rubber layer, the protective rubber layer made of a fiber-reinforced rubber composition contains 10 to 50 parts by weight of short fibrous reinforcements, 20 to 70 parts by weight of carbon black, and 100 parts by weight of rubber base consisting of 20 to 100 parts by weight of natural rubber or isoprene rubber and 80 to 0 parts by weight of butadiene rubber, the short fibrous reinforcements oriented in the tire circumferential direction.