cthree

That's about the size of it. If you have it handy like you would if you raced in a series with tire changes then why not? If you don't it's a pain in the balls to carry around a couple of bottles (you at least need a spare), regulators and to evacuate your tires/wheels in a vacuum before filling them with pure dry N2.

Helium on the other hand is pointless since it requires the same overhead, is expensive and has a molecular density not much less than air (just enough to make a balloon weighing almost nothing gently float up). The volume of Helium you would put in a tire would make no measurable difference to the weight of the tires and wheels (it would make a difference but it would be so small you couldn't measure it on even the most accurate scales).

The Reverend

Uhhh... I think I covered everything you said.

mikegarrison

Helium trivia: do you guys know where helium comes from? Wells.

Even though it is the second most abundant element in the universe, it is too light for the Earth's gravity to retain in the atmosphere. So the air has essentially no helium. But it is produced deep underground by radioactive decay processes, and it is found mixed into natural gas. That's why we get it from wells.

More on topic, this is why helium is relatively more expensive than nitrogen, which can be gotten almost for free just by separating it from the air.

macr88

Maybe it has nothing to do with moisture but more of a gas thing??
water boils at a temperature of 212 at 14.7 PSIA
Most people run tire pressures at around 44 PSIA.
Wouldn't this greatly increase the boiling point above race tire temps?
Is the water changing state if not then would we get any measureable amount
of pressure increase from the water. It's just going to be droplets of water in
the tire not vapor. Without a change in state the increase in pressure is
probably not measureable. As a gas I think its a greater change in pressure.

Hmmmm?
I'm confused

payneinthe

At 38PSI, the boiling point of water is 130C, which is right where the tire temps are, meaning the water vapor is in a state of transition between droplets and vapor. As a droplet, it has no contribution to overall pressure, but once it evaporates, it has some contribution. The exact contribution is not readily apparent, but I'll look into it, just to satisfy everyone's curiosity.

WarrenW

Actually, I was just joking when I said helium. That's what the was for.

Warren

rlaifatt

I thought I said helium first (as a joke too), but now I see that you had mentioned it before me . One idea I had to handicap a competitor was to secretly replace the air in his tires with heavy argon .

macr88

Are you saying 38 PSIG if so you have to add 14.7 to that. That's if your running
38 PSI on the gauge.

twohoos

The air temp inside the tire does not equal the tread temp. I'd be surprised if the air temp ever got anywhere near 100C.

l8brakr

^Yeah but what are your brake temps that heat up the rim that the tire is mounted on? I can easily see the air temp inside the tire getting that hot.