Process for making radial tires

Claim 1

A process for making a pneumatic radial tire comprising forming a carcass means having at least one rubberized carcass ply directly on a cylindrical former, securing a pair of highly flexible side rubber layers in spaced relation to said carcass ply to form the outer part of the sidewalls of the tire, said carcass ply consisting of cords disposed at 70° to 90° to the equatorial direction of the tire, said side rubber layers consisting of a flexible rubber having a Shore A hardness upon vulcanization of 40° to 55° , forming a green case by forming the carcass means and side rubber layers into a toroidal shape, securing a rubberized breaker layer and a preformed tread rubber layer to the tire crown, said breaker layer consisting of cords disposed at 10° to 30° to the equatorial direction of the tire, said tread rubber layer consisting of a central body portion having a width equal to the width of the tire crown and at least a portion of the shoulders and being made of a highly abrasion-resistant hard rubber material with a Shore A hardness upon vulcanization of 55° to 75° and in addition a pair of edge portions made of flexible rubber material like said side rubber layers and integrally prebonded to said central body portion to cover the opposing side edges of said central body portion, the overall width of said tread rubber layer being wider than the spacing of the pair of flexible side rubber layers, forming the tread rubber layer around the toroidal shape of the green case to place the edge portions of the tread rubber layer in overlapping relation with the adjacent edges of the flexible side rubber layers, securing the overlapped edge portions of the tread rubber layer directly to said flexible side rubber layers so that the entire outer surface of the sidewalls of the toroidal-shaped green case is protected by said flexible rubber, and vulcanizing the thus builtup toroidal-shaped green case.