In the past two weeks the local tire stores have been advertising replacing Air in your tires with Nitrogen. Claiming all sorts of benefits, cooler running, better mileage ,
tires last longed. Has anyone done this and what has your experence been? Charges run $2.99 to $4.00 per tire,914 and 3 other cars. Is this a job? Thanks Dave

Isnt the air we breath like 80% nitrogen to begin with. Pure nitrogen is moisture free. That has to be a benefit for tires, right?

werd

though we do sometimes use pure nitrogen in our tire.. depending if the generator is off etc

well, I'm a chemist, fwiw. Nothing wondrous about nitrogen - its just a cheap gas. The important thing is that it wont have water in it which would lead to unpredictable pressure changes as it liquifies/evaporates with temp changes. But I suspect these changes would only be relevant on a race car, if at all. Also, water can cause havoc with aluminum wheels. A couple times I've had to have tires dismounted due to slow leaks caused by corrosion on the sealing surface.

I'd say if it ain't broke, don't fix it. Plain old air works pretty well in tires. And, as mentioned, that's 80% nitrogen already. And I think that the air coming from most compressors is gonna be drier than normal; the water comes out when you compress it, and I think (help anybody ?) theres a valve of some sort that lets the water out so as not to sit inside the compressed air tank and cause rust. As for mass, oxygen is so close to nitrogen that that couldn't matter. In some cases, getting rid of the oxygen might help prevent chemical reactions (oxidation) that cause materials to age, but that's happening on the outside of the tire regardless, and I don't think that affects lifetime.

Short answer : don't waste your $$$.

I've been told that nitrogen doesn't change pressure based on heat nearly as much as 'air'. No personal experience...

-aaron

Thats true because as said above the lack of moisture in it helps keep pressure changes more linear and predictable. There are alot more variables acting on the pressure when there is water in the air; its not an easy PV=nRT equation anymore, there are partial pressures and such.

Got my tires at costco last year and the tire pressures have been very stable. ...They use nitrogen. I likes it!

Yep, Costco will do it for free (for members). I put it in my car and noticed zero difference. I think it is just a gimmick. Besides, there is no way to bleed all the air out anyway when the nitrogen goes in. Eddy

Thats what I heard also....
My Michellin supplier told me the same thing. Nitrogen keeps the preasure stable during temp changes. Its going to be the new thing of the future, do to low profile tires and new car computorized air preasure warning systems. but I can't see it being a big difference in my 195/60/15 tire

Later

I used to use NO tanks to drive my air tools when at the track.....I also use it to pressurize underground tanks when doing leak decay tests.....cheap and inert...like me....

Old racer trick for years and the new flavor of the day at the tire shops to get the dickheads in.....

When I was in aviation we used it for all of our tires. We also had magnesium alloy wheels. It was because of the corrosion resistance, low moisture, and its linear pressure change curve.

I don't personally think that it matters for our applications.

it'll only work if you can somehow get all the "old" air out of the tire first. on racecars, you'll have to bleed and refill several times, each time getting rid of a bit more oxygen. the benefit is a tirepressure that does not change quite as much with heatchanges.

i'd say, for a street car, save your money ...
Andy

[quote name='brp914' date='Apr 22 2006, 04:33 PM' post='665240']
well, I'm a chemist, fwiw. Nothing wondrous about nitrogen - its just a cheap gas. The important thing is that it wont have water in it which would lead to unpredictable pressure changes as it liquifies/evaporates with temp changes.




I am surprised that you did not pick up on the most simple reason for the nitrogen

Nitrogen is lighter than air, it makes the car seen faster because you think it is

lighter. Duh..

Carefull....Not all nitrogen is created equal. We've had problems with the race car tires. Yes, if you always got completely pure nitrogen, it would be moisture free. But if you show up at the industrial gas supplier and buy your tank of nitrogen, it's got moisture in it. In a race car, you'll go crazy trying to figure out why some tires are gaining more pressure for no apparent reason. For a street car, imho, it's a waste of money.

Matt

So, how long before helium becomes the racey tire gas of the year?

Doesn't nitrous give you a tremendous buzz?

I think you should try nitrous.


M

BTDT, that's my excuse

I agree with Matt on the grades. In the semiconductor industry pure nitrogen is the common spec'd gas but for pneumatics and non-process purposes they use CDA (clean dry air).

I suppose for economies of scale, I'd expect an exotic gas in a Carrera GT but not in a common car...