Nitrogen

[Original Poster]

Original post.....

[orange911]

No difference in fuel mileage as long as pressure is the same. N2 is less affected by temperature than air, so pressure remains uniform over higher temperature gradients.

[boba]

Initially N2 was used by race teams to better manage tire pressure build up on track. This is due to the lower relative humidity of N2 vs compressed air. Even with a dryer on your compressor the N2 has less moisture.

It was then picked up by track day folks to get that extra advantage. Now guys at cars & coffee can talk about their N2 filled tires.

Does it help manage pressure build up, Yes. It also has some other slight advantages but none that you would likely notice.

I would not pay extra for it but it does get sold by the tire dealers and my Porsche dealer. Remember if you do not purge the tire you will still have ambient air (moisture) in your fill. Think of it like all those dealer add on's which have very little value and very high profit margin.

[RSTarga]

Thats all costco uses at their tire centers. It's a pain if you have to adjust pressure and don't have it. As was mentioned above in racing it is used as it is less affected by heat than normal air with humidity and is constant and eliminates the expansion variable.

[boba]

It's a pain if you have to adjust pressure and don't have it.

Not a problem, just add compressed air, they mix.

If they do not purge the tire prior to setting the pressures there is already ambient air inside. Don't let the marketing hype make you crazy.

If you have it and want to use it by all means go ahead it will do no harm.

Be skeptical if you are being sold it.

[boba]

Raj,

If you have N2 around and want to use it, it will not hurt anything.

There are 2 other benefits of N2 which you can determine the value of.

Because the N2 molecule is larger it is less likely to leak out of your tire, not that air leaks much.

Because N2 is inert it has less degenerative effect on the tire then ambient air which can have some containments which will cause the tire material to break down more quickly. Most of us will wear them out before the break down. And since the outside is still exposed they will still be good on the inside when the outside is gone.

When we had N2 bottles around all the time to run our tools in the pits and for our race wheels, sure I would use it. I would not pay a premium over the cost of air or go out of my way to find it.

[texas911s]

Exactly,

In the race car our optimum pressure is 21lbs. On a hot day with air we start at 14. With nitrogen we can start at 17lbs. Quicker to get up to speed and less change.

Also with nitrogen i dont worry in off season or with the rains that dont get used as often. No/less dry rot. Air will dry rot the tires quickly stored.

Finally. I owned tire store for a few years. Sold now. Not one of my finest investments but nitrogen was a selling tool for the manager to the guys with nice cars. Dont think it helped them much but they liked the idea....

Don

[davep]

Dry air contains roughly (by volume) 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.038% carbon dioxide.I think that unless you really purge the tire with nitrogen, you are likely just going to reduce the non-nitrogen content from 22% down to about 7%. I don't see that it is really worth it, but hey, if you have deep pockets....

[Flieger]

I think the reduced water vapor content of nitrogen is more important than taking away the oxygen,argon,etc. The water vapor changes the pressures more as the tire passes through the dew point temperature. Oxygen and argon do not condense out from gas to liquid, which process causes a significant change in pressure. The phase change from liquid to gas also takes a lot of energy without raising the temperature of the water, which I suspect could cause a plateau of tire temperature, complicating setup.

[John Z Goriup]

Raj,

If you have N2 around and want to use it, it will not hurt anything.

Because the N2 molecule is larger it is less likely to leak out of your tire, not that air leaks much.

The first documented use of pure nitrogen as the medium to keep tires inflated at relatively constant pressure was in the first part of the twentieth century in Europe during 6-day bicycle races.

The very thin latex inner tubes of "sew-up" tires ( for their weight saving) as used on the racing bicycles permitted leakage of air, whereas inert Nitrogen with its larger molecules ( as noted above) couldn't "make it to freedom" through the Latex inner tubes of the day. Since air compressors were not permitted in the crowded track infields which served as the "pits", the mechanics could bring pre-inflated wheels and have them at the ready when needed, for the duration of the races.

There is no real-world advantage to justify the use of Nitrogen in road car tires. F1 however and classes of racing where slicks are used / permitted, employ it almost exclusively for the advantage of much lower swings in temperature related pressure changes, ergo much more constant chassis-height, maintanance of which is vital to overall vehicle aerodynamics.

JZG