REINFORCED CONSTRUCTION OF BEAD PORTIONS OF RADIAL TIRES FOR HEAVY LOAD VEHICLES

摘要

A reinforced construction of bead portions of radial tires for heavy load vehicles such as tracks, buses etc., which is well balanced in rigidity and which has an excellent durability is disclosed. The construction comprises a first reinforcing layer and a second reinforcing layer, said first reinforcing layer being substantially continuously extended from a height covering both the upper ends of said second reinforcing layer and of the turn-up portion of the carcass ply to the inside surface of the carcass ply, said second reinforcing layer being interposed between the turnup portion of the carcass ply and said first reinforcing layer, the axially inside portion of said first reinforcing layer which is disposed along the inside of the carcass ply having an upper end whose height h1 from the bead base portion is given by h1 = (0.8 to 2.5)h0 where h0 is a height of the end of the turn-up portion of the carcass ply from the bead base portion and composed of at least two layers whose cords are inclined on a circle formed by the end of the turn-up portion of the carcass ply with respect to the radial direction of the tire by an angle between 40.degree. and 75.degree., and the axially outside portion of said first reinforcing layer which covers the outside of the second reinforcing layer being composed of at least one layer.