Nitrogen fill for tires... the truth?

euro911sc · euro911sc's Garage

Just read this page:

POWERTANK - CO2 Air Systems

Fairly convincing, but thought I would probe the knowledge of the board. If the results on this page are correct why do teams have bottles of N2 to fill the tires with? When I did tires at the last 24 I would pick them up from Conti. and drain them, fill them with N2, drain again, and refill with N2 again. Yet if there are no noticeable benefits why bother?

Thoughts?

-Michael

na2ub · 08-11-2011, 11:46 AM

I believe nitrogen expands / contracts less with temperature changes, hence some people use that on the track to keep their tires in a narrow range of pressures. Also, nitrogen molecules are bigger than the mix of molecules in air, so they don't escape through the pores in the rubber as fast, meaning you don't have to add air very often.

Eagledriver · 08-11-2011, 11:55 AM

Unfortunately gas characteristics don't care what you believe. The only possible advantage of N2 over air is if the air introduces liquid water into the tire. If liquid water is in the tire when cold and vaporizes when the tire warms up then the pressure will increase more than a tire with pure gas. There are two reasons race teams use N2. One is it's a cheap and easy way to have high pressure gas for air jacks, tires, shocks, tools, etc. The other reason is some of them think it works better. It works just like power bracelets, shoe magnets, eco water systems, glucosamine, ginko, etc. (placebo effect).

-Andy

na2ub · 08-11-2011, 01:02 PM

Maybe race teams use it for the non-flammable aspect. They are always very concious of things going up on flames.

Tom W · Tom W's Garage

Nitrogen is NOT bigger than 'air'. Air is 78% nitrogen with 21% oxygen and 1% argon and other minor components. The difference in size between an oxygen molecule and a nitrogen molecule is not meaningful when talking about permeability through tires.

I use nitrogen because it is easy, not because I have observed a difference in control of tire pressure when compared to reasonable dry air. A nitrogen tank is cheap and a lot easier than hauling around a compressor.

winders · 08-11-2011, 03:43 PM

Nitrogen is no better for tires than dry air, which is ~78% nitrogen anyway, or any other non-combustible dry ideal gas. The problem is trying to find dry air. Nitrogen gas has no water in it so getting nitrogen is the easiest and cheapest way to get a dry gas for your tires.

Water content is the enemy because water expands at greater rate than an ideal gas like nitrogen does.

If I could find a place that sold compressed dry air and it cost less than nitrogen, I would use it in a heartbeat.

Scott

Mahler9th · 08-12-2011, 08:21 AM

Scott: your statement about water needs refinement from a technical standpoint.

I have noticed a difference between air and nitrogen in my tires.... this is based on where I got the air! I prefer the modest benefits of nitrogen because they are augmented by all of the other stuff I can do with it. For example, driving a cut-off tool to trim my fiberglass quarter panels for additional tire clearance at the track because I changed my ride height.

There are plenty of threads on this on the internet since it first started and plenty of "speculation" and so on before that. I am sure that you can find plenty of technical information describing various ways to produce compressed dry air and how that compares to nitrogen gas... perhaps even in some type of peer-reviewed scientific publication, and/or in some graduate school library of theses/project reports.

A big nitrogen tank can be a pain (I have one), but it costs $40 to fill. For me it is easier than monkeying around trying to get comparably dry air from my Sears compressor. And it is really cool to be able to drive tools with gobs of pressure when I wanna, even in my garage. Yippeee! Great for buzzing off those rear axle nuts. And I don't have to monkey around with compressors and generators at the track.

I am sure some (many?) race teams have personnel that don't really know the facts about nitrogen, as Andy suggests. Tire changers don't need to have advanced degrees like Tom W. and I. But I am also sure that in general the community knows what's up... it is a handy tool like many others they use.

As an aside, a friend of mine had his large nitrogen tank standing upright with the regulator attached at Sears Point recently. It was simply "tethered" to his trailer with a short strap at the top. When he went to hitch his trailer to the truck, he knocked over the tank (the strap broke). The tank hit the ground right on the regulator, which snapped off. Imagine what happened next. Good thing that Andy and Tom did not see that!

euro911sc · euro911sc's Garage

Ease of use is a great driver of product adoption

Thanks guys.

winders · 11:06 AM

Quote:

Originally Posted by Mahler9th

Scott: your statement about water needs refinement from a technical standpoint.

Mike, why don't you refine it for me?

I didn't want to go into a long dissertation on what happens when water is present. If you want to get into a discussion on the vapor pressure of water, how temperature and pressure affects the vapor pressure of water, and how all this works out inside a tire with water (as a gas or a liquid) in it, feel free.

I don't see how your "advance degree" makes one bit of difference here. Electrical Engineering, right? Doesn't apply here. Tire changers need to be very careful not to use too much lubricant. Why? Because too much lubricant introduces water which would defeat the purpose of using Nitrogen in the first place.

Scott

JP911 · JP911's Garage

Quote:

Originally Posted by Mahler9th

As an aside, a friend of mine had his large nitrogen tank standing upright with the regulator attached at Sears Point recently. It was simply "tethered" to his trailer with a short strap at the top. When he went to hitch his trailer to the truck, he knocked over the tank (the strap broke). The tank hit the ground right on the regulator, which snapped off. Imagine what happened next. Good thing that Andy and Tom did not see that!

Oh crap!!! That must have been something to see/hear. I have a small Nitrogen tank I use to top off my shocks and I keep it strapped down in about 10 different ways when I transport it. I suppose I have a somewhat irrational fear of the pressurized gas.

Tom W · Tom W's Garage

My tank is secured via what I believe is a DOT approved cradle and strap (bolt to secure the strap and cradle welded to the frame of the trailer). We use gas tanks all the time and do not take any chances that might yield a problem like Mike notes. OSHA takes a very dim view of things like that.

Mahler9th · 08-12-2011, 11:57 AM

Scott:

Never, ever drive with a chip on your shoulder! I mean a race car, not a keyboard.

I think you can do better than this statement without a dissertation, but it is no longer relevant:

"Water content is the enemy because water expands at greater rate than an ideal gas like nitrogen does."

You will find out soon about tire lubricant and the rotation of the rear tires on the wheels, et cetera. Your tire mounting vendor(s) of choice will curse your arrival every time unless they are Roger Kraus Racing, Aim Tire, 650 Racing or the like. When I visit my service provider, I help them to take the sting out of the process, and we lubricate liberally! You'll see!

juanbenae · juanbenae's Garage

Quote:

Originally Posted by Mahler9th

Scott:

Never, ever drive with a chip on your shoulder! I mean a race car, not a keyboard.

I think you can do better than this statement without a dissertation, but it is no longer relevant:

mike, way to take the high road with a true delta bravo. if some race as efficent as they type knowing it all bob s. in the 12 car & I at the back of the PRC spec pack better watch our mirrors for faster traffic coming up on us. pretty soon anyway, gotta get to the track before you can win, i reckon....

t

winders · 03:18 PM

Quote:

Originally Posted by car 311

mike, way to take the high road with a true delta bravo. if some race as efficent as they type knowing it all bob s. in the 12 car & I at the back of the PRC spec pack better watch our mirrors for faster traffic coming up on us. pretty soon anyway, gotta get to the track before you can win, i reckon....

t

Except that Mike and are friends and he and I are are harassing each other....

...and there was nothing wrong with my point about water and how it expands faster than Nitrogen in a tire. Why? Because in a tire, water does indeed expand at a greater rate than Nitrogen or other ideal gas. How? Well, as the tire heats up, more of the water content becomes water vapor and that water vapor takes up more space than liquid water. So, as the tire heats up, the pressure rises faster than if no water were present. This is why dry air is just as good as Nitrogen. Nitrogen is easier to find than dry air which is why it makes sense to use Nitrogen.

Scott

Mahler9th · 08-12-2011, 06:38 PM

t: I hope that I get to see you at Thunderhill... the weekend is always better when I get to visit with friends like you!

That nitrogen tank I mentioned did not go anywhere because of the way the regulator broke, thank goodness. The driver and owner of the tank is a new father and his wife was pushin' the baby around in a stroller a lil earlier... Thanks goodness...

Anyway, a good reminder for all of us in the paddock and when transporting these tanks. And yikes, don't get them anywhere near an MRI system!