Tire pressure using nitrogen

[okloneranger]

I have a totaly stock 02 ACR with Michelin pilots. At cold pressures using air, I go with the factory recommended 29 PSI all around. At the end of say a 30 minute run, a re-check gives me a reading of 31 PSI. I've been told of the advantages of using nitrogen gas instead of air in tires: cooler running tires,no rust or corrosion to wheels inside, no deterioration of tires inside, slower leaks in the event of a punture-nitrogen molecules are larger than air molecules, and more stable tire pressure. I've emailed Michelin concerning my Question of what pressure to use, but all they said was go with factory recommendation. So, i'm looking to those of you out there with experience in this area. How much, if any will the pressure vary using nitrogen? If pressure doesn't vary would you go with 31 PSI cold using nitrogen? I have been a member for about 3 months, this is my first thread, and i've had my viper for 7 months. Thanks.

 

[Luke@tirerack]

[FONT=Verdana, Helvetica, sans-serif]I can't see where nitrogen, oxygen, argon, CO2, methane, radon, or whatever else you might want to fill your tires with would matter. So long as it remains a gas at any reasonable tire temperature, it won't matter. (OK, maybe radon wouldn't work so well, as it would turn into lead over the course of a few days.)

But then, what about things that don't remain a gas? As in water vapor? The air in your compressor is probably saturated with moisture unless you live somewhere very dry. So you start with 100% humidity, and lets say a temperature of 110F. Now lets say your compressor is at 90 PSI and your tire is at 35 PSI. That will give you enough moisture in your tire to start to condense at 80 degrees. So as the outside temperature drops, you will get condensation, and the pressure will fall faster than Boyle's law.

If you have a small compressor tank so that your fill air is hotter, or worse yet a 12V tire filler that is spitting condensed moisture directly into the tire, obviously things get worse.

[/FONT][FONT=Verdana, Helvetica, sans-serif]I'm not a big believer in this nitrogen fill stuff, but it isn't completely bogus either. Dry air fill would be just as good.[/FONT]
[FONT=Verdana, Helvetica, sans-serif]
and Nitrogen molecules are not larger than O2 molecules:

From my Perry's Chemical Engineers' Handbook
At standard conditions (0°C, 1 atm):
density of air = 1.2928 g/L
density of N2 = 1.2507 g/L
density of O2 = 1.4289 g/L

They are all pretty close, and O2 is acutally a bit more dense than N2.


oh yeah ... 29 psi
[/FONT]

 

[dave6666]

[FONT=Verdana, Helvetica, sans-serif]I can't see where nitrogen, oxygen, argon, CO2, methane, radon, or whatever else you might want to fill your tires with would matter. So long as it remains a gas at any reasonable tire temperature, it won't matter. (OK, maybe radon wouldn't work so well, as it would turn into lead over the course of a few days.)

But then, what about things that don't remain a gas? As in water vapor? The air in your compressor is probably saturated with moisture unless you live somewhere very dry. So you start with 100% humidity, and lets say a temperature of 110F. Now lets say your compressor is at 90 PSI and your tire is at 35 PSI. That will give you enough moisture in your tire to start to condense at 80 degrees. So as the outside temperature drops, you will get condensation, and the pressure will fall faster than Boyle's law.

If you have a small compressor tank so that your fill air is hotter, or worse yet a 12V tire filler that is spitting condensed moisture directly into the tire, obviously things get worse.

[/FONT][FONT=Verdana, Helvetica, sans-serif]I'm not a big believer in this nitrogen fill stuff, but it isn't completely bogus either. Dry air fill would be just as good.[/FONT]
[FONT=Verdana, Helvetica, sans-serif]
and Nitrogen molecules are not larger than O2 molecules:

From my Perry's Chemical Engineers' Handbook
At standard conditions (0°C, 1 atm):
density of air = 1.2928 g/L
density of N2 = 1.2507 g/L
density of O2 = 1.4289 g/L

They are all pretty close, and O2 is acutally a bit more dense than N2.


oh yeah ... 29 psi
[/FONT]

I'm sure you didn't mean that literally Luke, but a tire filled with oxygen to 30 psi in a fire would be REALLY bad. Remember the fire triangle? Fuel, heat, and yes, oxygen.

None the less a good post. But if you can get hooked up with a cylinder of N2, why not inflate your tires with it. You can knock it off the list of things to worry about. And you could actually make some money selling tire fills to your friends. I think some tire stores around here charge several $ per tire for the N2.

 

[B767DRIVER]

Nitrogen is used in the tires, struts and hydraulic accumutator of large aircraft. I asked one of our mechanic about the expansion of nitrogen and was told the nitrogen will expand approx. 10% under high heat. They can only get an accurate reading of tire pressure after the aircraft has been on the ground for 3 hours. I have seen this on a friend's Viper at the track. His tire pressure was increasing about 10% with track tires. I was using normal air and I was getting approx. 20% or greater increases in pressure.

 

[Luke@tirerack]

but, those aircrafts go up in the air and fly around in temps well below zero unlike a car ... heck they don't even fill tires with nitrogen at the Indy 500

 

[Venomiss]

I am sure many already know this, Costco uses nitrogen. Have not seen it for use in a Viper but we have it another family car. This is a good post and thanks for the information Luke. ( You helped us with another car that we replaced tired on recently).

 

[B767DRIVER]

but, those aircrafts go up in the air and fly around in temps well below zero unlike a car ... heck they don't even fill tires with nitrogen at the Indy 500

True...After touchdown and braking those same cold tires reach temps. that our cars will never... I'm not recommending one way or the other...I don't run nitrogen. Okloneranger just asked if nitrogen pressure would vary....Yes. Approximately 10% or so.

 

[Luke@tirerack]

I personally use 78% nitrogen in all of my tires

 

[dave6666]

I personally 78% nitrogen in all of my tires

Air.

Ha ha ha ha ha ha ha ha....

 

[ViperTony]

I personally 78% nitrogen in all of my tires

Say it ain't so...I feel so dirty, I need to take a shower.