Patent ID: 7337817

Claim:
A radial tire having a body ply extending from a tread section to sidewall sections and turned up over bead cores of bead sections to have turned-up portions at both sides thereof; a belt layer wound on an outer circumference of the body ply in a tire circumferential direction; a tread circumferentially wound on an outer circumference of the belt layer; and bead fillers extending from the bead cores radially outward between the sidewall sections and the turned-up portions of the body ply, wherein: the belt layer comprises at least one spirally wound belt layer in which one or plural belt cords coated with rubber are arranged to be spirally wound substantially in parallel with the tire circumferential direction; and the belt cord in the spirally wound belt layer has a property that an increase rate of tensile load to stretch rate is small in a range of a predetermined stretch rate or less but is large in another range exceeding the predetermined stretch rate, and wherein the belt cord in the spirally wound belt layer has a property that the stretch rate is equal to or greater than 0.5% at tensile load of 20 N, and wherein the tensile load is equal to or greater than 60 N at stretch rate of 3% of the tensile load or is equal to or greater than 30 N at the stretch rate of 1.5%, wherein: the body ply is arranged to be at least one layer; body ply cords of the body ply are inclined at an angle in the range of 85 to 90 degrees relative to the circumferential direction; and the belt layer arranged on the outer circumference of the body ply comprises two oblique belt layers in which belt cords made of steel are arranged to be inclined in the same direction at the angle in the range of 30 to 60 degrees or in the range of 40 to 50 degrees relative to the circumferential direction and at least one spirally wound belt layer in which a belt cord made of a hybrid cord is coated with rubber and is arranged to be spirally wound on outer circumferences of the oblique belt layers substantially in parallel with the tire circumferential direction; and of the two oblique belt layers, one oblique belt layer is in the range of 40 to 70% of the other oblique belt layer in width and is circumferentially arranged at a center portion in a direction of the radial tire width.