Structure for reinforcing bead sections of radial tires for heavy loads

Claim 1

A reinforcing structure at bead sections of radial tires for heavy loads, comprising; (1) at least one carcass ply composed of rubberized cord layer arranged radially or semiradially, which is turned around a bead cord from inside to outside of the tire, (2) a circular composite rubber stiffener being disposed between a case main portion formed by the carcass ply and the turned-over carcass protion, extending outwardly in radial direction of the tire from bottom end adjacent to the bead core and composed of a lower half rubber stock portion having a higher modulus and an upper half rubber stock portion having a lower modulus, said upper half portion being arranged along the end portion of the inside of the turned-over carcass ply, (3) at least one chafer composed of rubberized metal cords crossed with the ply cords being disposed in a circular region at the outside of the turned-over carcass ply so that said chafer end does not extend to the turned-over carcass ply end, and (4) a reinforcing member composed of at least two rubberized organic fiber cord layers arranged in bias, which are disposed directly in contact with the composite stiffener along the case main portion or secured to the inside of the ply cord of the case main portion and crossed with the ply cord and crossed with each other, said reinforcing member being locked with the bead base and disposed along a circular region of a radial height h 1 of said reinforcing member end from the bead base being 0.85-2.6 times as high as a perpendicular height h 2 of the upper end of the chafer from the bead base, the organic fiber cord being crossed at an angle of 50° to 60° with respect to the ply cord of the main case portion near the position of the point crossing to the axial direction line passing the turn-over end of the carcass ply.