Patent ID: 6311752
Filing Date: 2001-11-06
Classification: B60C,Y10T

Abstract:
A pneumatic radial tire comprising: a radial carcass having at least one rubberized cord ply reinforcing a pair of sidewall portions and a tread portion between a pair of bead cores embedded in a pair of bead portions, said radial carcass comprising a main carcass body extending between the pair of bead cores and a turnup portion wound around the bead cores from an inside of the tire toward an outside thereof, a stiffener rubber taperingly extending between the main carcass body and the turnup portion from the bead core toward an end of the tread portion, said stiffener rubber being an integral structure of two or more rubber compositions having different hardnesses, wherein a rubber composition having a highest hardness among said rubber compositions is located near to the main carcass body as a hard stiffener rubber member and a rubber composition having a hardness lower than the hardness of the hard stiffener rubber member is located along the turnup portion over the hard stiffener rubber member as a soft stiffener rubber member, and the hard stiffener rubber member being convexly projected toward the outside of the tire at a cross-section of the tire in a region sandwiched between a normal line L.sub.V drawn from an end of the turnup portion perpendicular to an outer surface of the main carcass body and a line segment L.sub.H drawn from the end of the turnup portion up to the outer surface of the main carcass body in parallel to a rotating axial line of the tire, and a height of the hard stiffener rubber member from the outer surface of the main carcass body on a normal line L drawn from a top of the convex projected portion perpendicular to the outer surface of the main carcass body is at a maximum in a region ranging from the line segment L.sub.H toward the end of the tread portion.