No one seems to be able to answer the OP's original Question! I say let the OP try out NO2 in tires and report on his/her findings. Little NO2 cyclinders were available in gourmet kitchen accessories shops like Williams-Sonoma and (at one time) Brookstone's. They were used for making Whipped cream in soda syphon-like container(think of the Three Stooges spraying seltzer at each other....). One added Cream to the syphon; infused the NO2 into the cream and the syphon spat out perfect whipped cream. Unfortunately, these little cannisters were used as a semi-legal way of getting high, back in the seventies and early eighties- they were known as "Whippits". The NO2 was inhaled as "laughing gas" and a little stupidity ensued. Because these were being bought in ridiculous quantities by high schoolers, various retailers began to limit the amount that could be bought by an individual or at what age a buyer would be permitted to get them. That being said, one can find them via an internet search as "whipped cream chargers". This is what came up on the first try on Google: http://www.easywhip.com/whipped-cream-chargers.html. If you have a Gourmet supply store in your area, I wouldn't be surprised if they had a few boxes in stock. Happy Hunting!