Compressor air or Dry Nitrogen

[crazycurrie]

How many of you actually use Dry nitrogen in your race tires as opposed to regular compressed air?? Whats the diffrence. I know that Dry Nitrogen doesnt expand or contract to heat and cold so you never have to worry about your tire PSI increasing as it becomes HOT. As where regular air has moisture in it that actually turns to steam and eats away at the inner carcus of the tire, as tire temp increases causing the PSI to increase during a race.
I ask cause the comment came up that dry nitrogen actually escapes through the tire itself.. I dont beleive that to be true, but what do you think? ;D

[duc995@aol.com]

I have never heard of anyone using "Dry Nitrogen."  All gases change in volume with changes in temp and pressure...remember high school science? ;D

The change may be reduced by the lack of water vapor, but tires don't reach the boiling point of H20 (unlike brake fluid) so you don't have too worry about steaming your wheels! :D

All tires are somewhat permeable to nitrogen...air is almost 70% nitrogen!

[TreyBone]

Regular air out of a bicycle pump ;D

[james-redsv]

How many of you actually use Dry nitrogen in your race tires as opposed to regular compressed air?? Whats the diffrence. I know that Dry Nitrogen doesnt expand or contract to heat and cold so you never have to worry about your tire PSI increasing as it becomes HOT. As where regular air has moisture in it that actually turns to steam and eats away at the inner carcus of the tire, as tire temp increases causing the PSI to increase during a race.
I ask cause the comment came up that dry nitrogen actually escapes through the tire itself.. I dont beleive that to be true, but what do you think? ;D

I think you are crazy, very misinformed or you must a comic.  ???

[Super Dave]

I the bias ply race tire time, this was a practice as tires would get hot.  Basically, you tried to manage the heat with tire pressure, or nitrogen for some.

Now, with the radials, they just don't run "hot" so to speak.  

So, regular air is fine.

[bweber]

The only point in using nitrogen is that is it 100% dry, so there is no water vapor introduced into the tire.  Not necessary for motorcycle racing in my opinion.

[KBOlsen]

John used nitrogen when they were campaigning their dragbikes.  

[SE#39]

The hot setup for tires is a mixture of -- 78% nitrogen with 20% oxygen and 2% trace gases such as argon.
A "dry Nitros system" into the airbox is an altogether different setup.

[Zac]

Fill 'em with helium, save a little weight  ;D.  Now helium WOULD permeate right through the tire faster than air, them ity bity molecules.

-z.

[tzracer]

Nitrogen is used instead of air because the water vapor in air gives an inconsistant pressure rise as the tire heats up. I doubt most people racing at the club level would notice a difference.

[fourandsix]

Actually Nitrogen is better.

[MZGirl]

Assuming this is a legitimate concern, and not trolling...

Ok, I will define the "system" as the tires and volume of gas within the tires.  First off, this system is not hermetically sealed.  The tires are organic materials that act as a permeable membrane.  Molecules of volatile gases can move back and forth through this membrane (in AND out, following Fick's Law of diffusion).  So even if you put dry nitrogen in the tires, it would become "wet" due to the moisture absorbed by the organic compounds (and it will mix with volatile chemicals escaping from those compounds...more on that later).  Now, you could desiccate the volume to try to keep the gas dry, but the system wants to obtain equilibrium (again, it's not sealed) and the desiccant would eventually become saturated.

Regular air does have moisture in it, but it's not going to turn into steam in your tires.  It's already in the vapor phase!

The "inconsistent pressure rise as the tire heats up" is due to a change in the compressibility factor, which is very slight.

I wouldn't worry about water vapor.  You know that funky smell that new tires have?  Well, your tires are made of organic compounds that contain volatile chemicals.  Over time, those volatile chemicals escape, which is what you smell.  And yes, they do escape into the interior and mix with the gas inside the tire volume.  Again, nothing to worry about.   ::)