Abstract: A pneumatic radial tire having a carcass layer of cords disposed substantially at a right angle to the circumferential direction, and four belt layers sandwiched between the carcass layer and a tread. A pair of belt layers composed of a second and a third layer in the direction of from the carcass to the tread of the tire have cord layers crossing one another respectively at an angle of 10.degree. to 30.degree. to the circumferential direction, fatigue resistance of the cords of the second layer being significantly greater than fatigue resistance of the cords of the third layer.

Abstract: A pneumatic radial tire having a bead portion in which at least two reinforcing layers comprising a steel cord reinforcing layer and a fiber cord reinforcing layer are arranged outer to a turnup portion of a carcass layer and are covered with a rubber stock, the bead portion being capable of exhibiting an enhanced durability.

Abstract: In a pneumatic tire of a structure in which a belt-reinforcing layer is overlaid and interposed between a tread and a carcass cord layer, the belt-reinforcing layer consisting of a transient-reinforcing layer positioned in contact with the carcass cord layer with its reinforcing cords disposed at an angle of between 40.degree. to 75.degree. with respect to the circumferential direction of the tire, and at least two belt-resistant layers, the lower one thereof being laid over the transient-reinforcing layer with its reinforcing cords disposed at an angle of between 15.degree. to 30.degree. with respect to the circumferential direction of the tire, and the upper one with its reinforcing cords disposed at an angle of between 150.degree. to 165.degree. thereto, the tire is improved in that the carcass cord layer is formed of a single layer and the reinforcing cords in the carcass cord layer are arranged so that their angle with respect to the circumferential direction of the tire is between 75.degree. to 85.