This disclosure is directed to a tire retreading machine which includes a chamber adapted to receive therein a plurality of stacked tires adapted to be retreaded therein, the chamber having an inner surface, and inwardly therefrom there being a radiant heater, a porous or perforated shield, and an imperforate or nonporous shield with the latter being axially shorter than the former and both shields being spaced from a bottom surface of the chamber such that upon heat being generated by the radiant heater, hot air convection currents are set up within the chamber flowing generally upwardly adjacent the chamber inner surface and flowing generally downwardly between the imperforate shield and tires within the chamber to create substantially uniform curing or retreading temperature throughout the chamber, lessening temperature gradients or hot spots, and also allowing radiant heat to pass through a lower portion of the porous shield adjacent the bottom surface of the chamber to augment temperature uniformity through the chamber, the tire retreading machine also includes a novel mechanism for opening and closing an upper end of the chamber utilizing a cover which is moved linearly along a path defined by coincident axes of the cover and the chamber, and also along an arcuate path between an open position of the cover and an out-ot-the-way position thereof.