The water in the air is what expands whacky in your racecar.

Any "air" with low moisture content will be nice and stable.

I'm not worried about 2-3psi drop per year change based on some crazy ideal lab condition, I change my tires that often anyway - at least the rears.

 

"Whacky" is a relative term. Even if you fill the tire with VERY humid air (100% relative humidity), the pressure variance between compressed air and compressed Nitrogen will be less than 1 PSI. I think one would have to be a very skilled driver indeed to discern such a difference.

However, I concede the PLACEBO effect. The human mind is an amazing thing. If one believes they can go faster with Nitrogen, maybe they can. There is just NO science to support the many claims.

 

I could tell the difference of 1psi on my motorcycle at the track, so I'm willing to bet the heavy track guys with a few thousand track miles can tell the difference.

Static pressure at fill wouldn't change, it is under load and heat conditions - steam or humid air doesn't act as ideal as the rest of the stuff gases over the tire's operating range.

I'll concede the placebo point, as well as great marketing from some tire shop owners.

 

.. Damn hit send too soon.

You've also got real water in there sometimes, not just vapor or moisture!! It doesn't act like a gas at all under 212F!

 

^^^ I dunno maybe it is placebo effect...but it seems to feel better on track...

 

Nah you're just more susceptible to the whacky effect.

Actually you are likely one of the few with enough track miles that can feel a difference.

 

Not that it changes anything, or the conclusion, but I talked to a couple of guys today at a flow meter company today. They told me it's closer to 99% percent pure.