Tire building drum

A tire building drum for assembling and shaping tire carcasses toroidal, comprising a central durm, and two side drums, an inflatable membrane carried by said central drum, inflatable membranes carried by said side drums, means forming radial grooves located between the central drum and each side drum, a core supporting ring and membrane supporting ring both of elastomeric material having a shore hardness A of about 90.degree., said membrane supporting ring located axially outwardly of, adjacent to, and in overlapping contact with the core supporting ring to form a composite cylindrical ring structure axially spanning said groove, and flanges located in said groove, one of said flanges being connected to the axially inward end of each core supporting ring and extending to the bottom of said groove at the axially inward edge and one of said flanges being connected to the axially outward end of each membrane supporting ring and extending to the bottom of said groove at its axially outward edge, said flanges consisting of annular discs with bent interconnected movable portions with the bends of the core and membranes supporting rings flanges being in mirror image so that when radially collapsed alternate bends in each pair of core and membrane supporting rings flanges contact each other and contact the side walls of the groove and when radially expanded the bends are substantially removed from the flanges and they are pressed out of contact with each other and against the side walls of said grooves, and means to introduce air pressure between said flanges to radially expand the flanges and thus the core and membrane support rings attached thereto and supported by said flanges.