Originally Posted by
ShortLegCyclist
My understanding is that it has to do with the partial pressure gradient, in other words, there is such a much higher concentration of CO2 in the tire after you inflate it than in the ambient air that the CO2 tries to escape to equilibrate that imbalance.
When you pump up with air, you create a gradient due to the higher pressure, but it's not as extreme as the gradient between pressurized 100% CO2 and the partial pressure of ambient CO2 in the atmosphere.
Good point. The concentration of CO2 in the atmosphere is something like 0.04%. An inner tube with close to 100% CO2 will have an incredibly steep gradient to force those molecules through the tube.