Abstract: A tire building apparatus comprising an expandible former embodying axially movable former expanding and contracting means to dispose the former in positions defining firm supporting surfaces of different radii, said expanding and contracting means ensuring symmetrical expansion and contraction of the former with respect to a transverse plane of the former. Axially-movable tire bead core locating and supporting means are disposed on opposite sides of said transverse plane. Further means, for example at least one rack and pinion mechanism connecting the two bead core locating and supporting means, is provided to ensure that axial movements of the two bead core locating and supporting means occur symmetrically with respect to said transverse plane.