Originally Posted by
ItsJustMe
Wait, air is 70% nitrogen. Are you saying that CO2 molecules are smaller than nitrogen atoms and therefore leak out faster? That sound HIGHLY dubious to me. In fact it sounds completely implausible. If that's not the reason I'd love to hear the mechanism behind CO2 being leakier than nitrogen.
The nitrogen in the air is N2, not single N atoms. And it has to do with more than the raw size of the individual atoms. Nitrogen has a larger effective size than you might expect because the electron cloud is relatively diffuse. I'm having a hard time finding good comparative information on size between nitrogen gas and carbon dioxide, (it doesn't help that they are differently shaped) but you can rest assured that CO2 does diffuse out a tire more rapidly than air. It's not that big a deal, though, and there's really no need to do anything other than top off the tire when it gets low, as normal. I don't carry CO2 cartridges myself. They seem kind of wasteful to use for routine flat repairs.