Anyone run nitrogen in their tyres?

[project.r.racing]

Weren't the two gases a poofteth difference in weight? And the nitro going in is pressurized mixing the two within the tyre? So how does one 100% purge all oxygen?

[madjak]

I think the theory is that the normal air in the tyre contains 20% of stuff other than Nitrogen. That stuff has some things in it that are responsible for the largest increase in volume due to temp increase (mostly moisture I think ). So if you purge that 20% down to 2-3% eith pure Nitrogen then you have significantly reduced the amount of pressure increase due to temp.

So you pump it in at one valve and release it out the other. If you pump in 10 times more Nitrogen than the volume of the tire then there will be pretty much pure Nitrogen in the tire.

I think most motorsport teams use bottled air rather than compressed air or Nitrogen as bottled air has low moisture content and works just as well.

[lonesailor]

Without a comment on pros v cons of nitrogen in tyres, when testing a new or repaired refrigeration system it is evacuated to as near a perfect vacumn as possible, this allows any moisture in the system to boil off ensuring a dry system. It is then charged with dry nitrogen at the highest working pressure of the system and left for a time .If the pressure stays constant -regardless of ambient temperatures-the system is leak free.Note that the leak test is not done with air prior to evacuation, which would be easier,as variations in ambient temperatures can vary the pressure causing uncertainity as to the leak free status of the system.

[StillIC]

In summary, if you wish to maintain the most constant tyre pressure with increasing tyre temperature, ensure there is no moisture in the gas in the tyre, and, if you are really pedantic, then use a high molecular weight gas. Low molecular weight gases like He and H expand the most for a given temperature change, and high weight gases the least. So maybe Radon is the best gas for the job?