In critical applications tires are inflated using pure nitrogen (link).
But carbon dioxide (CO2) is a larger molecule (will leak slower from the tire), as well as inert (will not oxidize rim and will not combust in case of an accident). (link)
Also, from the ideal gas law, pressure is proportional to the density, individual gas constant and temperature. Assuming constant volume (i.e. P ∝ R*T), any change in temperature is "amplified" by the individual gas constant. And the gas constant is in favor of CO2:
R(CO2) < R(O2) < R(N2). (ref) So CO2 seems to give better pressure stability over temperature fluctuations.
Also, CO2 storage is cheaper than nitrogen storage.
So why tires are inflated with nitrogen and not CO2?