PUR NRG

Background: I play paintball, which means I have both a 4500psi, 68ci carbon fiber air tank and a regular 50lb nitrogen steel tank. For purposes of tire pressure the important thing is no moisure gets into the tire--at least that's my understanding of why NASCAR crews fill tires with nitrogen. Nitrogen itself isn't better than high pressure air, it's just easier to get.

So it occurred to me that for a minimal cost (regulator and hose fittings for CF tank, hose fittings for steel tank) I could run nitrogen in the tires and use the CF tank at events to top off air pressure.

The small size and light weight (5 lbs) of the CF tank is an obvious advantage on grid. My question is would running moisture-free nitrogen in the tires be of any benefit at autocross or track events? Or are the runs too short for any real benefit to occur?

nk_Rx8

One of the tire places I use fills the tires with nitrogen. It supposedly is more resistant to temp related volume changes. So your tire pressure doesn't rise as much after heating up.

Ophitioxaemia

just plain old air is 78% nitrogen. in fact to make liquid nitrogen they cool air (my dad told me this).

i thought boyles law says expanding gas expands the same amount no matter what it is. been a while since chem class tho

james

PUR NRG

[sigh] Please re-read the second sentence of my original post. It's surprising how many people across several forums have missed that point.

Ophitoxaemia

sorry, i was responding to a *response* to your post, you were indeed clear about what you meant.

all the national champions in my region use just plain old air. i know, ive borrowed andy mckee's air compressor before. :D

james

GoBerserk

I say any benefit is a real benefit. Practicing with, and then running on Nitrogen will probably give you, if not better, then, more consistent times and your car will more predictable if you don't have to worry about changes in tire pressure.

Ophitoxaemia

to recap: nitrogen will not help you with pressure changes with temperature. you need a non-gas for that.

incidently, have anyone taken any tire temps on the stock setup? i will take my pyrometer this weekend and do some spot checks.

james

Hollywood Zoom

Claims:
improved fuel mileage
extend tire life
improved handling / performance

Did my tires at costco (free to members) no purchase necessary
do google search on NITROGEN FOR TIRES to find out more.

I felt and heard the difference right away - less road noise / smoother ride

PUR NRG

Chances are the reduced road noise and smoother ride came from the new tires, not the gas inside them. Potenza S-02s are notorious for this where they get really noisy as they wear down.

All three claims stem from having a more uniform tire pressure. You can get the same benefit by checking PSI every week.

On one hand the performance gains are not that significant. On the other they are significant enough that people looking for the slightest edge might consider it. Sorta like icing down the headers between autocross runs.

Doctorr

What the Sam Hell you been smokin?

S

Hollywood Zoom

I didn't buy new tires from costco - same tires driven on same roads - 4000 miles on them
Have you tried it or is this just a speculative statement?

Hollywood Zoom

are you offering smokes? please elaborate beyond a simple statement.

Gomez

Okay, nitrogen is superior to air in tyres as it has a larger molecular structure. Think of your rubber tyre as a membrane with tiny holes in it. Some of the smaller oxygen molecules escape through it which reduces the tyres pressure. This leads to poor mileage, poor handling, and a lesser tyre life.

The nitrogen molecules, being larger, have a more difficult time negotiating their way through the membrane. Hence, a tyre filled with nitrogen only will maintain it's pressure longer. That's why nitrogen is better. But it is dearer. Buy some good alloy/metal valve caps and stop the loss of air through your valves. Your tyre pressure will be maintained at the correct pressure for longer and you will have all the nitrogen benefits for bugger all cost!

Or, check your tyre pressures weekly with an ACCURATE gauge.....

Regards, Gomez.

beachdog

In Popular Mechanics this month, Jay Leno talks about some of the special equipment he has in his garage. He uses a nitrogen generator to fill the tires on his fleet.

cgrx

I have a membership at Costco - do I just go to the garage and ask for nitrogen?

Spazm

As do I...please do tell.

dannobre

iTrader: (3)

Since air is approx 80% Nitrogen anyway.....................don't get that it will make a big difference

Napboy

so many naysayers. i'd like to see more testaments, but after reading some stuff on the net, i don't see any mentions about any performance gains. They only mention benefits of keeping tires inflated properly.

RotaMotion

Hmmm, this has me curious. Anyone heard anything about how Nitrogen expands with heat vs. regular old air (ROA?)

StealthTL

iTrader: (1)

What a load of crap!

Improved fuel mileage?
Jay Leno does it?
"I can feel and hear the difference right away."?

......and if the oxygen leaks out, but the nitrogen doesn't, everybody would eventually have (low pressure) nitrogen filled tires, right?
Which also doesn't happen.

Come on people, a tire with 30 psi of air and one with 30 psi of nitrogen would be absolutely the same, and impossible to tell which is which.

Sometimes I despair at the gullibility of the average customer.

S

ScudRunner

Um...maybe I didn't pay as much attention in school as I could have, but I'm not sure it works that way. Gas under pressure is gas under pressure, regardless of molecular structure. If you have a tire with 30 psi of oxygen, nitrogen, xenon or whatever in it, then introduce a hole, the tire will leak gas out of the hole at the same rate; this is because gases, by nature, have no volume.

Gomez

I've had my say....don't believe me? It's a free world, believe what you want! I didn't say nitrogen would not escape, I said a nitrogen filled tyre would maintain it's pressure "longer".

"Lurch, answer the door, the sceptics are knocking!"

Gomez.

arattle

Thank you, finally someone who doesn't just buy whatever is posted on the internet! It is a complete load of crap, indeed. Molecular weight of nitrogen (28) and oxygen (32) is so close, that at 30psig and with the tiny volume of each tire, the weight gains will be so insignificant, I dare anyone to actually calculate them. Especially since 79% of the air you have in your tire right now is already nitrogen. The only benefits would be to reduce corrosion, but this has never been an issue with consumer car wheels. Aircraft tires, shocks, and struts use nitrogen to reduce corrosion, limit the flammability, etc. But not for "performance gains". This is laughable.

EDIT: And to address Gomez's comment....well, I'll just let it go, since I'm not at all interested in starting any flame wars. But let's just say that rubber, by nature, is impermeable, just like polymers, glass, etc. I mean...you can keep 5000psig nitrogen in a *metal* flask without any losses for years. What kind of loss will you have in a couple months from a *rubber* tire? The only volume losses will be due to initial heat of compression - but even then, your tire pressure normally fluctuates with external temperature changes.

-arattle

Gomez

Look, rubber is not impermeable...rubber is porous. Why do rubber balloons filled with helium deflate quicker than balloons inflated with air? "Cos a helium molecule is smaller than an oxygen or nitrogen molecule, the main two components of air. The helium leaks through the balloon skin at a greater rate due to it's reduced molecular size.

Oxygen which makes up approx 20% of air has a smaller molecular structure that of nitrogen, which makes up approx 80% of air. If you put air in a tyre, then the oxygen component of air will be diffused through the porous tyre carcass at a greater rate than that of nitrogen. Ipso facto, a tyre inflated with pure nitrogen will hold it's pressure longer than the same tyre filled with air.

arattle, nowhere in this thread did anyone mention using nitrogen as a weight saving measure, so I don't know how that came up in your argument! Although nitrogen is lighter than oxygen, for the volumes of gas we are talking about it is worth bugger all, I agree!

Back to the title of this thread though, does nitrogen give you an amazing performance boost? No, but it will allow you to go a little longer between stops to inflate your tyres. Worth it,...... not IMHO. Air is free. As I and PUR NRG said earlier, just check your tyres weekly. Buy some decent valve caps.

Play safe, Gomez.

PUR NRG

To all the skeptics: as Gomez suggested in his first post, try Googling for info about nitrogen filled tires. It's fine if you don't believe him (and even I think his claims are exaggerated) but try doing some basic research to back up your arguments.

Nitrogen filled tires does two things:
1. Nitrogen gas leaks out through the rubber slower than normal air. Proven fact but has nominal benefit. Checking your PSI every week would give you almost the same benefit. Properly inflated tires means better gas mileage, reduced wear on tires and better grip.
2. Using a nitrogen fill means the gas going into your tire is dry. This is the key benefit. Ever blast air at a gas station air hose to make sure there's pressure? Notice how sometimes a spray of water mist comes out? If water or water vapor gets into your tire, that water will turn to steam/vapor at higher temps, which increases the PSI in the tire. Overinflating tires is as bad as underinflating.

You can get the same effect by using compressed air (like you fill scuba tanks with) because that air is dry too. Dry air also has the benefit of following Boyle's law and makes estimating/controlling PSI at a given temp easier.

Race teams looking for every edge use nitrogen fill tires. This is not bullshit. This is proven science. If you want to refute then please cite sources to back you up.