well I hope the valves are rated to 400 psi as thats roughly the pressure of propane at 50C. can you supply the spec of the valves you use? somehow I dont think the car tyre valves will rated for that sort of pressure.i use propane on mine and the torches never get taken off the bottles because i fill them using a shrader valve that is soldered in to the bottle. been ok for the last 15 years