Mike Murphy

FYI - most good air compressors have air driers installed in the lines, which helps with the moisture. If you're using those cheap gas stations ones (which we are all forced to use on occasion), and you see water coming out of the hose, you know you're getting a lot more than just air!

Mike Murphy

The TLC TV show "MythBusters" did some tests using a helium-filled football vs. an air-filled football. The test revealed that the football was indeed slightly lighter, but also slower through the air on a long field-goal kick or throw. The reason is that a lighter football still has the same coefficient of friction, but with a reduced mass, the football slowed down faster when traveling at high speeds.

In the end, the tests showed no real difference between the two, but it was still interesting.

Smokin

Nitrogen molecules are slightly larger than the regular air that goes into tires. You'd think that since the atmosphere is 78% nitrogen that this really wouldn't be an issue... But it is with some people. You lose less air out of your tires with pure nitrogen. It's becoming a selling point at a lot of tire dealers in my area. I think it's more hype than anything... But if I had a choice I'd probably go with 100% nitrogen

I won't even mention the Hindenburg...

Garth S

Oxygen diffuses through the butyl rubber inner liner found in all (tubeless) tires moderately faster than nitrogen: as O2:N2 is ~ 20:80 in air, after a few months of routine tire pressure top-ups, the internal N2 concentration becomes substantially >80%.
Play your time with this when inflating tires with air, and one ends up with essentially a 'free' nitrogen fill ....
The real enemy is moisture: while freezing is the issue with aircraft, in performance cars, water becomes a gas at 100C ... and can jack the pressures up suddenly.