Doughan

Anyone put nitrogen in their tires? My service center offers a lifetime nitrogen tire service. The benefits are supposed to be better gas mileage and longer tire life. Has anyone done this and are the benefits worth it?

newgene

I've never really heard of anyone doing it, but I would think the possiblle benefit would be from a lower moisture content. This may help prolong the life of the tire sensors (then again maybe not), but it may add some minor cost to filling it. However, I wouldn't think you could find a nitrogen fitting that would allow you to fill gaseous nitrogen into a tire. I don't see any harm in doing it. Just remember that too much of it in a low ventilation area can be hazardous. Just my $0.02.

16Again

When NASCAR had the Sportsman series we ran nitrogen in our tires. It keeps the pressures steady and does not absorb moisture. We used a standard valve and air fitting, nothing fancy is needed.
Bob

bierbelly

What a lot of crap. Air is 80% nitrogen, only about 20% oxygen. Longevity? How often do your tires dry rot before you wear out the treads on them? That's really the only possible benefit from excluding the oxygen. Besides, oxygen from the air will permeate into the inside through the tire itself eventually.

BTW, so will moisture.

SpeedyZ

We use it all the time in the race car. The pressure don't change as much with temperature change as does air (due to less water vapor). We also run the air tools off the bottle at the track. Much easier than lugging around an air compressor, and it fairly cheap. I still have a bottle of nitrogen laying around, I plan on running it in mine when I get it back together. I don't see how it could hurt anything.

How much do they charge for that service?

Doughan

$50 for a lifetime service.

b98

what's next spend your money on go fast mods.

bierbelly

Table I Gas thermal conductivities as a percent of the conductivity of air at 1ata and 300 K. (KGAS / K AIR)

GAS

Nitrox H2 He Ar CO2 SF6 CF4
(0%-100%)

100% 695% 563% 67% 62% 50% 62%


Table II Absolute gas thermal conductivities K at 1 ata [cal/cm K sec], (Reference 3).
GAS Nitrox
(0%-100%) H2 He Ar CO2 SF6 CF4 Rn
KGAS 6.18 43.5 36.3 4.23 3.87 3.33 4.06 ~ 0.97

A little something scientific from http://www.decompression.org/maiken/Why_Argon.htm

Note that the thermal conductivity of any mixture of oxygen/nitrogen, from 0% to 100% has the same conductivity as air.

Little hard to format a table on here.

Clay Assassin

The "The pressure seems more reliable" defies all science:

Lets take a look. Air IS 80% Nitrogen.
At low pressures gasses are pretty much equal, and pretty much ideal. They follow charles law.
So any change in pressure due to temperature will be exactly the same.
Look that up in your High School Chemistry book.

Next idea: Pressure stays more constant because it doesn't leak out as much? The oxygen molecule is large and weighs more than a nitrogen molecule. So diffusion will be slower. - Collage Mass Transfer.

I'm not even going to look up the thermal conductivity to see if thats the same.

So the only remotely possible benifit is due to the oxidative properties of the oxygen no longer being present. The gentlemen that said moisture and oxygen will eventually go right through the sidewall into the tire gets an A in his Mass Transfer course, recognizing the laws of diffusion. However we could be waiting a long time.

We'renot talking lightbulbs here, where we fill them with Xenon so they run cooler (Way heavier than Oxygen, like 4 times).

I would love to see any real argument that explains how it's better, justifying the extra cost. Even if it's pennies.

LoneStarFRC

Hmmm......lessee here. If you got presurized nitrogen (meaning higher than ambient or out side pressure) inside the tire, then how ezackly is this oxygen supposed to "permeate" into the tire? Magic?

bierbelly

No, physics. Differing gas concentrations on either side of a membrane (the tire wall) will tend to equalize, since there's a higher partial pressure of one (oxygen) outside, it'll force it's way through the membrane to equalize the concentration inside (up to 20% O2...well, really 20.9%, but who's counting?).

RPOZ16

May just be marketing, but Costco is offering it free when they sell and install tires.

98stocker

Wish i could get lifetime nitrous fill ups for 50 bucks...

newgene

I agree 100%! It was the combination of Boyle and Charles who put it all together. Starting with:

PV = mRT; where P1 x V1 = m1 x R1 x T1 for state 1

m1 = (P1 x V1)/(R1xT1)
m1 = m2 (because it is sealed tire and mass doesn't change from state 1 to state 2)
R1 = R2 (gas constant doesn't change from state 1 to state 2 in either case)
V1 = V2 (calling tire expansion negligible; this is the only place where the difference in gas constant can effect the pressure. It would be a next to nothing difference)

So, the difference would be:

P1/T1 = P2/T2 in either case. In theory, they should be identical.

bierbelly

The only possible benefit would be to use a gas that doesn't absorb heat as readily as air. Nitrogen doesn'twork...after all, air is 80% nitrogen. Now if you were to put Argon in, it wouldn't heat as readily as air or nitrogen, but over the course of a race, the temperature would be the same as for air.

On the other hand, one of the things air does for tires (besides inflate them) is to help remove the heat from the rubber; for example, if you run a tire low on air, it can fail because it overheats due to insufficient air volume to absorb the heat. In that case, you'd rather use a gas that has a greater ability to absorb heat than air, like hydrogen or helium. Those wouldn't last in a tire too long, since the molecules are so small. But they would reduce the unsprung weight!

h0ldmyplace

If there is no benefit to using Nitrogen, how come aviation tires are filled with it?
Fighter jets and all types of aircrafts use it so obviously there is some benefit tothis gas. I will try to find out what it is in my squadron and pass it on.
Luis

bierbelly

It may have something to do with the fact that air compressors condense moisture in the compressed air. A lot is usually knocked out with a trap, but some still exists. At high altitude, obviously it'll further condense and freeze. Compressed nitrogen from liquid N2 is very dry, powers of ten less moisture than compressed air. I don't know why the presence of a little ice inside the tires would cause a problem.

Or maybe the military has been sold a bill of goods too. After all, they buy $400 toilet seats...

George8211

And if you live in California add 26% polution to those numbers

TURBO VET

Airplanes use it because nitrogen will not support fire. If there is a fire in the wheel well the tire will melt and supply more O2. Airplane tires are inflated to around 200psi and that is alot of air pressure in a tire.

mwagne16

Better yet, how often do they dry rot from the inside out?

Stop it stop it stop it!!!

Damn this is as old as the hills. You're not racing F1! Forget this already. If it's free, fine. If not, put your cash in your pocket and move on. Supra's were talking about this over 10 years ago. ENOUGH! It was here 6 months ago. Not again. Fill the back with baloons. It will lighten the car.