Abstract: Pneumatic tires are disclosed, which each comprise a pair of beads, a toroidal carcass composed of at least one carcass ply which extends between the beads and is composed of cords arranged substantially in a radial direction of the tire, a belt layer superimposed radially outside a crown portion of the carcass, a tread arranged radially outside of the belt layer to cover the belt layer, and an auxiliary layer which is arranged between the tread and the belt layer to cover the whole belt layer and is composed of an organic fiber cord arranged substantially in parallel with the tire circumferential direction. The tread is constituted by a tread central portion containing a tire equatorial plane, a pair of tread side edge portions covering the side edges of the belt layer, and a pair of tread intermediate portions between the tread central portion and the tread side edge portions.

Abstract: A pneumatic tire having a unidirectional tread pattern comprises a plurality of main slant grooves obliquely extending from an end of said tread toward a central portion of said tread and arranged at a given space in the circumferential direction of the tire, and at least two auxiliary slant grooves arranged in an island portion defined between two adjoining main slant grooves in the circumferential direction.

Abstract: To obtain a uniform initial cord tension in an auxiliary layer of a radial tire made up of a toroidal carcass, a belt, the auxiliary layer and a tread rubber, the belt is formed by winding inextensible cords around a drum with a radius of curvature substantially the same as that of a tire tread. Further, when the belt is formed by winding the cords around a flat drum, the auxiliary layer is formed on the belt by winding a heat-shrinkable cord around the belt in spiral fashion in such a way as to apply a higher tension at both the ends of the belt layer than at the center thereof. The radial tire thus manufacture is excellent in high-speed tire durability and tire uniformity, without causing belt separation trouble at high speed.

Abstract: To improve steering controllability and stability, radial tire treads are usually formed with a plurality of inclination grooves arranged on both sides of a tire tread at regular intervals along a tire circumference and extending from both tread ends to a main central circumferential groove at an acute angle with respect to tire equator so as to converge to the tire outer circumference. To further improve the steering controllability and stability on both dry and wet roads, the inclination grooves are formed asymmetrical on both sides of the tie tread. The inclination grooves with a large pitch length P.sub.1 and a small inclination angle .alpha..sub.1 are effective on dry roads, while those with a small pitch length P.sub.2 and a large angle .alpha..sub.2 are effective on wet roads.

Abstract: To improve the durability and the riding comfortableness of a pneumatic safety tire having at least one carcass ply, at least one belt layer, and a pair of crescent-shaped cross-section reinforcing layers, each of the reinforcing layers comprises a higher elastic rubber layer with a hardness of 70 to 85 in Shore A and an elastic modulus of 25 to 60 kg/cm.sup.2 and an anticrack rubber layer with a hardness of 55 to 70 in Shore A and an elastic modulus of 10 to 30 kg/cm.sup.2. The maximum thickness of the reinforcing layer is preferably 4 to 12 mm. Load applied to the tire during run-flat travel is supported mainly by the higher elastic rubber layer, and crack generation due to tire deformation is reduced by the presence of the anticrack rubber layer.

Abstract: A pneumatic radial tire for high-speed running vehicles has a directional tread pattern defined by one or two relatively wide circumferential grooves arranged in the central region and plural slant grooves arranged in each side region of the tread, and an aspect ratio of not more than 0.8. In this tire, the slant grooves are arranged in a herringbone form with respect to the equator without communicating with the circumferential groove, each of which extending from an initial end to a terminal end and being a folded line at a folding point corresponding to 0.3-0.45 times of the tread width that an inclination angle .alpha. of line segment inward from the folding point is 40.degree.-85.degree. with respect to the meridian of the tire and an inclination angle .beta. of line segment outward from the folding point is smaller than the inclination angle .alpha. and 0.degree.-50.degree. with respect to the meridian of the tire.