tire pressure

An old trailer tire (if maintained at 65 psi using air) would wind up holding only about 9% O2 eventually. At which point it would reach steady state and no longer lose O2 faster than N2. 

Since air is about 78% nitrogen, and I already have enough things to complicate my life, I think I'm going to continue to fill my tires with a mixture of 80% nitrogen and 20% oxygen, plus a little argon and increasing levels of CO2.  That way, if I ever fall off a bridge into a deep lake with our Pod, I can let the air out of the tires and have plenty of oxygen to keep me going until I can reach the surface.

And in its solid form [Kryptonite} it keeps Superman from pestering you while you're out camping.  He won't show up and want to change in your Pod.  

It wasn't like that in the movies!  They held it in their hands and it stopped Superman in his tracks.  If it was in a movie, it must be true; like when I see it in the internet.