Abstract: A heavy duty pneumatic tire comprises a tread, two side walls, two beads, a radial carcass reinforcement, and a belt composed of at least two plies of which cords are intersected in the adjacent plies. The radius of curvature of the contour of the tread appearing in a tire cross section including a tire rotary axis is asymmetrical with respect to the tire equatorial plane. A larger radius of curvature is given to the tread portion to be located outside when the tire is mounted to a wheel, while a smaller radius of curvature is given to the tread portion to be located on the inner side when the tire is mounted to the wheel. The difference between the larger radius of curvature and the smaller radius of curvature is not less than 70 mm. The rigidity of the tread is larger on the tread portion having the larger radius of curvature than on the tread portion having the smaller radius of curvature.

Abstract: Radial tires having highly improved durable life by using a rubber composition prepared by incorporating a given amount of a primary fatty acid having 6-10 carbon atoms and/or metal salts of thereof to a rubber for embedding rubber for steel cords in belt portion or carcass portion of radial tires. By further adding thereto cobalt salt of organic acids other than the above described fatty acids and/or boric acid or a metal salt of boric acid, the corrosion resistance of steel cords is synergistically improved.

Abstract: A composite material of steel cords and rubber having improved corrosion fatigue resistance and fretting fatigue resistance and a method of producing the same are disclosed. The composite material is produced by bonding rubber to steel cords through vulcanization. Before the vulcanization, steel cords are treated with a rust preventing material consisting of at least one particular surfactant and at least one particular film-former to form a protect layer on the surface of the steel cord.