48 of the heat exchangers 60 and 70 into the chambers 67 and 77 the hot mold and the heated curing bladder heat the tire for 1 to 6 mins or so until the rubber which has been forced or extruded into the vent passages is cured to the non plastic state during this time steam may be provided in the bladder then steam at a temperature from 165 u00b0 to 170 u00b0 c is admitted through steam inlets 68 and 78 to the steam chambers 67 and 77 and caused to circulate around the mold the steam inlets are kept open and maintained in communication with a suitable source of steam at the desired pressure the flow of steam from the outlets is preferably controlled by a conventional steam trap to dead end the steam and periodically drain off the condensate while allowing pulsed flow of steam through the inlets various other systems may also be employed it is usually preferable to omit dome steam and to employ the maximum safe internal water pressure in the curing bladder during the vulcanization of the tire if water is used in the bladder the internal water pressure is preferably in the range from 280 to 400 psig steam may be employed in the bladder during part or all of the curing cycle the steam pressure usually does not exceed 250 psig the modified mold of the present invention may be used for curing pneumatic rubber tires of various types including those.