Method of producing tire belts

A method of producing tire belts comprising a first step of attaching a first belt ply to a forming drum having, at least at its axial ends, curved portions whose diameters reduce progressively toward axially outer ends of the curved portions, said first belt ply having a width wider than an axial width of the forming drum and having an overhanging portion, a second step of expanding said forming drum so that diameters of said curved portions at axially outermost ends become a predetermined diameter smaller than a maximum diameter of the forming drum in said first step to deform the nonoverhanging portion of said first belt ply so to conform to the outer surface contour of said forming drum, a third step of folding the overhanging ends of the first belt ply back over axial outer ends of a second belt ply after attaching the second belt ply to a center portion of the first belt ply outwardly thereof, and a fourth step of attaching a third belt ply in plural layers onto said first and second belt plies outwardly thereof.