apen749

Hello All,

Is anyone using Nitrogen in your tires? A local TV station aired a report on this stating:

40% less air pressure fluxuation
30% increase in tire life
6% increase in gas mileage

Per them Nascar has been doing this for years. One tire place here in Jackson, MS is charging $21 for new tires and $28 for old tires. These tires have green caps on the stems. I was just wandering if this was a gimmick.

Thanks, Lee

wi54545

Nitrogen is used in aircraft tires. It does better with heat I suppose...

Charlotte944

Not a gimic. Nitrogen has been used to fill radar wave guides for as long as I can remember.

Normal "air" is 70% nitrogen, about 18% oxygen, with the remaining 2% made up of other gasses. This "cocktail" of gasses does not expand in a linear fashion when heated which causes non-linear fluctuations in tire pressure.

Road hazards aside, the leading cause of tire failure is improper inflation.

streckfu's

Aviation uses it mostly because it is inert.

75ohm

That would be ~78% Nitrogen, ~21% Oxygen, and ~1% Inert gases...

eohrnberger

Begs the question. Would you get better gas milage if you pumped your tires up with Helium?

The logic is that by doing this, it would reduce the down fornce on the tires, however, the mass would be the same. I imagine that it would reduce the amount of parasitic drag by the tires, but that's about it. Anyone else?

For the other end of things, I've heard that in some construction equipment, their tires are filled with liquid chloride for more weight, so as to get better tracktion.

BlueDog944

Here's the one big problem with the whole nitrogen theory.... it works great if the tire is FILLED with nitrogen. Meaning... for the full effect you need to remove all the air first and then replace it with nitrogen. I don't see any tire shop that will take the time to deflate the tire as much as they can after it's mounted before they inflate with nitrogen.

Our team tried this when we were racing karts on the big road courses. What the benefit is, when the tire gets worked, the pressure doesn't grow nearly as much. Instead of setting pressure at 18 expecting it to grow to 22 during a race, we could set it at 19 and see it grow to 20.

Manning

The issue with inflating your tires with regular air is that it contains a lot of moisture and a crappy compressor can add in even more. The moisture heats up and dramatically changes the pressure inside the tires. We went to a tech session a couple weeks ago and one of the mechanics for Freddy Baker's T1 GT3 told us about a tire he pulled off a customer's wheel that had a HUGE quantitly of water in it, most likely from using a crappy gas stations air compressor. Nitrogen you would use to fill you tires is going to be from a gas cylinder and is most likely free of any moisture. You would see huge benefits from simply adding an air drier to your compressor line to help extract out any moisture before you put it in your tires.

mroberts

Helium wouldn't work - it wouldn't last more than a few days before leaking out - look at helium balloons.

I heard something abotu being able to get about 50% of the benefit of N2 by mounting, then just releasing the pressure of the air inside, and 90% of the benefit by sucking it down then refilling.

Matt H

The reason Nitrogen is used is that it seeps less through the innerliner of the tire. If you are checking your tires regularly (once a month) it is an absolute waste of money.

If you like the concept of people charging you for air, I suppose go for it. Yes, the tire should be completely deflated then reinflated, remove the valve core...air it up.

Checking them every month is free and a good practice to begin with.

Tires are mounted with no valve cores (unless you want them to blow up) so if you are using Nitrogen in your shop (which VERY few are because it is expensive for the proper equipment) you could just mount the tire and air it up.
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brad@tirerack.com

A few replies thus far:

Nitrogen is used primarily because it won't build or lose pressure in a tire due to buildup of heat. Race teams love it because they can better monitor pressure ranges.

Helium won't leak out of a tire, because the halobutyl liner of a tire won't let air or gasses out. Helium is pointless because you'd never have enough volume in the tires to do a thing. The tires would have to be 10 ft tall to hold enough to even start to lift the car.

Some wheels are now coming with two valve stems so that the oxygen can be purged from the wheel as its filled. The Kosei K1-TS, for example:

http://www.tirerack.com/wheels/Displ...Silver+Painted

Matt H

That is the gayest looking wheel I have ever seen, ricers will love them.

BTW, your answer is correct for a race team, it does not explain the reason grandma is having it done at Sam's Club (which is less propensity for pressure drop over time).
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inactiveuser92616

nitrogen is silly for a street car. The race team I work with in the summers uses it at the track only, and this is just because a nitrogen tank is a more convenient source of compressed air.

JBH

Here's what Air Liquide says: http://www.airliquide.com/en/medias/...es_filling.pdf

Manning

You all aren't explaining why the pressure of nitrogen out of a cylinder is not fluctuating more than the pressure of normal atmospheric air from a compressor. And it ain't O2 content, though the O2 will lead to degradation of the inside of the tire.

I'll give you an hint: moisture.