Abstract: A pre-vulcanized tread for installation on a tire casing includes a sole and an upper tread portion which are each arched between respective skirts. The arc of the sole differs from the arc of the upper tread portion by a predetermined constant. In the preferred embodiment, the skirts include generally planar interior and exterior wall portions, the skirts joining the sole along a radius which is less than the radius of the sole itself. The exterior sidewall is disposed at a predetermined angle with respect to the vertical such that the width of a nominal arc of the sole radius intersecting the exterior walls is of a predetermined length which is greater than the width of the upper tread portion arc, and the interior walls of the respective skirts are disposed at a different angle with respect to vertical such that an extension of the interior wall intersecting the nominal arc of the sole defines another arc width which is less than the width of the upper tread portion arc.

Abstract: A bead seal ring for use in the retreading of radial tires by use of a bead sealing ring unit that provides positive mechanical pressure for sealing the curing envelope between the bead sealing ring unit and the bead area of the tire by a radial force. In its relaxed or initial condition, the bead sealing ring unit has a diameter smaller than the bead diameter of the tire. The bead sealing ring unit is placed into sealing position and then expanded by a locking device secured to a metal band which is part of the bead sealing ring unit.