so I heard of some people filling their tires with Nitrogen gas.
Is there really any benefit to doing this?

 

From what I have heard the benefit is nitrogen will not expand with heating of tires. If tires are at 35psi then when hot they are 35psi still (or close)

 

Also leak less so maintain pressure longer. Something about the molecule size being bigger so doesn't pass through the rubber as quickly?

 

Air is 78% nitrogen, 21% oxygen, 0.9% argon ... leaving 0.1% for all the other stuff ... The ideal gas law ( P * V = n * R * T) - press * vol = # of moles * ideal gas law constant * absolute temp - applies to nitrogen as well as air. So basically you get the essentially same pressure change for a change in temp with pure nitrogen or dry air.

The pressure change will not be any different with nitrogen vs. DRY air for a given temperature change ... HOWEVER, if you have any liquid water that condensed in your tire from wet compressed air when you filled it ... eg. if you filled your tire from a DIY compressor without a dryer on a very humid, warm day you can get condensed water forming in your tires ... there is a reason compressed air tanks have a bleed valve at the bottom to get rid of water so they don't rust out ... as the tire warms up, any entrapped liquid water can turn to vapor and now you could have a higher pressure than expected ...

So one benefit in theory is the reduced water content in nitrogen - that of course assumes the nitrgen has lower water content than the ambient air ...

From what I have read however, the perceived benefits come primarily from getting rid of most of that 21% oxygen - it diffuses faster through rubber than nitrogen. The claim is that it can take 3-4x longer to get the same pressure loss from 95% pure nitrogen vs. standard compressed air. By maintaining a good pressure in your tire longer, you are promoting better handling, tire life, etc.

you can find lots of info from proponents of Nitrogen at http://www.getnitrogen.org ...

Me ... I just use my own crappy DIY compressor (without a dryer) and keep an eye on things ...

 

Acadian Dad,
Thanks for the facts. It is refreshing to see evidence on a post. I completely forgot that air was 79% nitrogen.
Apterr

 

Terrific info. Thanks much acadian_dad.

 

yeah it sounds interesting.. and the theory is great I think. But I wouldn't spend money on it for my street car. I don't think it's worth it

 

I think I paid around $230.00 for a small tank and regulator with hose. Tank is bigger than a scuba tank and I ran maybe 15 autox with it. Fill tire in AM to starting pressure and bleed after every run, do same for PM runs. Tanks that size cost about 130 new filled with N. Refill is not a lot. I now have 2 tanks in the nose of my goosneck trailer, piped to a hose reel in the back. Have a spare tank at home too. Maybe 2 tank fulls for the season.
Its biggest benifit is that it is dry and tires expand less when they heat up. I start my first run about 4 pounds below target pressure. If the day is hot and depending on the course, first run can sometimes put me 2-3 pounds over target.