Abstract: Continous extrusion means including a feed means arranged to supply feedback generally of substantaially circular cross-section to a circumferentially extending groove in a wheel,charterised in that machining means are poistioned to receive feedstock to the circumferentially extending groove,with the machining means being arranged to remove at least a surface layer from the feedback and from a circular cross-section dimensioned to be a close fit within the circumferentially extending groove.