A tire building drum and a method of building a tire carcass is disclosed. The tire building drum has a center section comprised of a plurality of segments that are radially and axially movable. The sleeve of the tire building drum over the center section has been eliminated, and instead has two seals located on the outer ends or shoulders of the center section of the tire building drum. The building drum further comprises shoulder sections that are axially movable. The shoulder sections include radially expandable bead locks. The method employs the steps of applying one or more carcass layers, locking the bead locks and moving the center section radially outwardly while moving the bead locks axially inwardly.