nitrogen in tires...

[reefer1114]

was flipping through pennysaver today and saw an advertisement for a tire shop who fills tires with nitrogen. first time i heard of this. claims to maintain better air pressure, lower fuel consumption, extend tire life, and eliminate rim rust. anyone have any experience with this and how much more is it?

[jdm538]

wow sounds crazy.. isnt that dangerous?

[ultraDorksGarage]

N2 in tires is an old trick. mainly a N2 molecule has less weeping characteristics(less pressure variances due to its larger size compared to the rest of molecules found in compressed air) compared to ordinary air. its also dryer due to its purity.

nascar used to do it, but now its banned in that series. Lemans was one of the first scenes where vaccuuming a tire then filling with N2 was seen.

[wootwoot]

"They" have been talking about doing it in cars from the factory for some time now. Sounds like a good idea to me

[krustindumm]

also pressure doesnt change with temperature as much...i've been told. seems to go against those physics laws though from HS, i think, i never really payed attention though.

[slivia-junkie]

if it is dry nitrogen then it will result in better balance since water will always tend to spin in the tire. and the larger molocule might resist weping better but due to the gas constant PV=NRT all gas will react the same at a given temp and pressure so it will change pressure just the same as air in different temps

[RBS14]

pressure doesn't change as much. It's not a defyance of the laws of physics at all. there is less moisture, so less expansion and compression. Also, Nitrogen molecules have different properties than oxygen molecules. Lets also not forget that "Air" that we fill tires with and breathe has something north of 70% nitrogen composition.

However, with these added bonuses of nitrogen, hardly any of them are noticeable unless you are racing or leave your car sitting for many many months or years without checking air pressure. It's basically just a big marketing tool to draw shops in to buy tires from them, instead of the competitors.

[Lurkable]

The "REMOVE" button is laughing at me...

[Jeff240sx]

RBS is right. 78.1% nitrogen in the atmosphere = 78.1% nitrogen in the compressed air inside the tires.
Also, on the PV=nRT, it's important to understand what it says. It's the IDEAL gas law. Not the all-encompassing total gas law.
For mixtures, like atmospheric air, that formula is too simple. It assumes a dry gas, usually a single gas. To account for mixtures, partial pressures are needed. To account for moisture content in the air, you need the steam tables and steam partial pressure.
Summary: Don't bring up equations you don't know how to use.
-Jeff

[S13 Charlie]

Wow! I haven't thought of steam tables and partial pressure since my thermodynamics class back in college! Thanks for the blast from the past!

I didn't know that Nitrogen was banned in NASCAR, I can't imagine why, I don't think it's a safety thing..

cheers,
C

[Jeff240sx]

I didn't know that Nitrogen was banned in NASCAR, I can't imagine why, I don't think it's a safety thing..

cheers,
C

I can't think of a reason, either. Seems safer to have a pressurized vessel filled with an absence of Oxygen to me...
-Jeff

[chuy]

My uncle races modifieds(dirt track) in Pa and he runs nitrogen in the tires to help them heat up quicker Ive ran nitrogen once as well. The tire gets to a certain temp and thats it nothing more and the temp slowly goes down. Didnt really see a diffrence in it other then the tire warms up faster and the temp all the way across the tire is some what even

[ultraDorksGarage]

Wow! I haven't thought of steam tables and partial pressure since my thermodynamics class back in college! Thanks for the blast from the past!

I didn't know that Nitrogen was banned in NASCAR, I can't imagine why, I don't think it's a safety thing..

cheers,
C


its a form of cheating...like using roller cams in the same series, better technology, but restricted.

and the pressure variance is not that it does not change... its that its more predictable, the pressure variance is from using compressed air toay at 70% humidity vs. race day at 50% humidity....its more predictable if u use a form of N2.

if N2 is 99.99% pure(we have 99.9999% LN2 in our factory) you know exactly what went inside your tire, whereas you dont know whats inside your tire when you use plain compressed air. predictability and repeatability is the thing race engineers look for.