Abstract: At least one reinforcing rubber layer is provided in the part of each of two side wall portions which is on the outer side of a carcass layer. The outer circumferential end portions of the reinforcing rubber layers extend to positions in which they are disposed between the end portions of the innermost belt layer and the corresponding portions of the carcass layer, while the inner circumferential end portions of these rubber layers extend inward in the radial direction of the tire so as to overlap the bead fillers in positions on the outer sides of the end portions of the carcass layer in the widthwise direction of the tire. A 100% modulus at 100.degree. C. of the rubber constituting the reinforcing rubber layers is not higher than that of the rubber of the belt layers, and a dynamic elastic modulus at 20.degree. C. of the former rubber in the range of 10-40 MPa.

Abstract: A rubber composition for a tire, comprising at least one compound selected from the group consisting of ascorbic acid and derivatives thereof, tocopherols, and citric acid and derivatives thereof.

Abstract: A pneumatic radial tire for a passenger car, which includes a plurality of grooves provided on the surface of a tread and extending at least in a tire circumferential direction and a belt having a double layer structure and provided within the tread, characterized in that the depth of the grooves is in the range of 6.0 to 8.5 mm, the thickness of a rubber under the groove defined as the distance from the bottom of the groove to the outermost belt layer is in the range of 0.5 to 2.5 mm, and at least one layer of the belt comprises aramid fiber cords coated with a coat rubber having a modulus of elasticity at 50% elongation of 30 to 55 kgf/cm.sup.2.

Abstract: A pneumatic tire having a bead in which an end portion of a carcass layer is bent from an inner portion to an outer portion of the tire so as to be turned up around a bead core, a reinforcing layer which consists of reinforcing cords covered with coating rubber being provided so as to extend along a turnup portion of the carcass layer, the hardness of the coating rubber in the reinforcing layer is set in the range of JIS Hs 65-95.

Abstract: A pneumatic radial tire having at least one steel belt layer disposed at a tread portion, wherein each steel belt layer is constituted by mixing and arranging at random a plurality of steel cords having a 1.times.2 twist structure of an S twist and a plurality of steel cords having a 1.times.2 twist structure of a Z twist, and has a mixing ratio of the steel cords having the 1.times.2 twist structure of the S twist to the steel cords having the 1.times.2 twist structure of the Z twist within a range of 4:6 to 6:4 and a difference in the twist pitch of at least 1.5 mm.