a radial ply tire for vehicle wheels has a torus - shaped body of elastomeric material which contains a belt - shaped reinforcing insert which has in the region underneath the tread of the tire a strip which is stretchable , pre - loadable and , under the influence of external forces , restorable in the circumferential direction of the tire . the strip of the reinforcing insert contains apertures extending largely transversely with respect to the circumferential direction of the tire . the apertures extend only partially through the strip in a transverse direction and are arranged in rows , the apertures being parallel and offset with respect to one another in successive rows . between them there are transversely extending unbroken portions which provide the desired transverse stiffness of the belt .