They sell kits at the bargain stores near me to convert old A/C freon bottles to an air tank--they will work on propane tanks too,but its kinda dangerous--its hard to get all the fumes out,and you dont want to fill tires with a mixture of propane and air,it could become explosive.I have a propane tank I converted,but I left it open to the air in my shed for several months to help dissapate the fumes--it still stinks like propane when I use it--I've been haunting my friend for a freon 30lb bottle,but he hasnt emptied one yet,its been a cool summer here,not many people had their A/C re-charged.If there were a better way to purge the fumes a propane tank would be ok,it will handle the 125 psi ok if its not rusty,but I dont know how to do it--I wouldnt want to be smoking a ciggarette while using the propane tank to air up tires! /forums/images/graemlins/weld.gif /forums/images/graemlins/thinking.gif