Wheels & Tires

[Jay3wheel]

Small point, but nitrogen is not inert.
Only those gases listed in the right hand column of the periodic table are inert
Your other points about nitrogen in tires seem correct.

 

[NSTG8R]

You are correct. Nitrogen is not a noble gas. But it's 'inertieness' [yeah...just made that word up] is close enough for manufacturing/industrial purposes. So I guess I started thinking of it that way years ago, and it stuck.

 

[Jay3wheel]

You are correct. Nitrogen is not a noble gas. But it's 'inertieness' [yeah...just made that word up] is close enough for manufacturing/industrial purposes. So I guess I started thinking of it that way years ago, and it stuck.

My understanding as to the reason nitrogen is used, is because it is denser than air. This provides greater shock protection, when the tire strikes something.

 

[Dustoff]

Homepage / Automotive / DIY Auto / Car Clinic Q&A / Is Nitrogen Better than Air in Car Tires?

Is Nitrogen Better than Air in Car Tires?

BY MIKE ALLEN
Comments

February 1, 2009 12:00 AM
[Broken External Image]

Q: Is there any advantage to using nitrogen instead of compressed air in tires? Will I notice improved fuel economy or a smoother ride? Will my tires last longer?

A: Sort of. From the top: Air is 78 percent nitrogen, just under 21 percent oxygen, and the rest is water vapor, CO2 and small concentrations of noble gases such as neon and argon. We can ignore the other gases.

There are several compelling reasons to use pure nitrogen in tires.

First is that nitrogen is less likely to migrate through tire rubber than is oxygen, which means that your tire pressures will remain more stable over the long term. Racers figured out pretty quickly that tires filled with nitrogen rather than air also exhibit less pressure change with temperature swings. That means more consistent inflation pressures during a race as the tires heat up. And when you're tweaking a race car's handling with half-psi changes, that's important.

Passenger cars can also benefit from the more stable pressures. But there's more: Humidity (water) is a Bad Thing to have inside a tire. Water, present as a vapor or even as a liquid in a tire, causes more of a pressure change with temperature swings than dry air does. It also promotes corrosion of the steel or aluminum rim.

If I ever need to top off a tire when I'm out on the road, I'll always briefly depress the tire chuck's valve with my thumbnail and vent some air. If my thumb gets wet, there's water in the line. Some gas stations don't do a very good job of keeping the humidity out of their air system. I don't even like to use a water-based tire-mounting lubricant unless I can let the tire bake in the sun for a couple of hours before I air it up and seat the bead. I've dismounted tires (not mine) that had several quarts of water inside—probably from a compressed-air hose that collected water and was never purged properly.

How is water relevant to a nitrogen discussion? Any system that delivers pure nitrogen is also going to deliver dry nitrogen. Filling tires with nitrogen involves filling and purging several times in succession, serially diluting the concentration of oxygen in the tire. This will also remove any water.

It's certainly simple, although time-consuming, for a tire technician to fill and bleed tires. But most shops use a machine that not only generates almost pure nitrogen by straining the oxygen out of shop-compressed air, but will also automatically go through several purge cycles unattended. Some shops have been charging as much as $30 per tire for this service. I think that's too much. If you're buying a new tire, it should be far less. Still, the nitrogen generator, filling system and technician's time aren't free—the dealer is entitled to some return for that.

So, to answer your specific questions: With nitrogen, your tire pressures will remain more constant, saving you a small amount in fuel and tire-maintenance costs. There will be less moisture inside your tires, meaning less corrosion on your wheels. You will not be able to feel any difference in the ride or handling or braking, unless your tire pressures were seriously out of spec and changing to nitrogen brought them back to the proper numbers.

 

[Smitty901]

The nitrogen thing has come up with motorcycles from time to time. It never goes main steam. While many of the claims are true about using it.
Just does not do much good.
Nitrogen is used in equipment that maybe used in explosive environments because it will not burn or promote burning . In highly explosive environments it is required.
Nitrogen unlike Oxygen does not seep or pass through the tire compound as fast. So tires hold pressure longer. Tires with nitrogen run a bit cooler, that can be an advantage in hot areas.
If you look at value stem covers those that are green have nitrogen installed.
Most I know seem to agree it is just not worth the effort and cost.

 

[NSTG8R]

My understanding as to the reason nitrogen is used, is because it is denser than air. This provides greater shock protection, when the tire strikes something.

Actually, and you made me look this up , "they say" nitrogen is 3% lighter than air. I just know we use it on aircraft tires because the stuff we're using (dry-pump) contains no moisture (important), as the name implies, and "possibly" because not being a mixture of gases (air) it'll have a more predictable expansion ratio at high altitudes.

Man...I'm learning some stuff today!

 

[JEBar]

I have been through 2 presentations from folks selling the nitrogen concept and equipment to the RV dealership where I worked .... for the last few years RV manufactures like Forest River have shipped many of their lines with nitrogen in the tires (the valve cap will be green instead of black) .... bottom line, for use in normal conditions its a gimmick designed to part folks from their money .... as has been noted, the air we breathe is 78% nitrogen .... if you read the details of most of the major studies (one of the first I read was done by Ford) they do show some modest (read that as tiny, tiny) advantages in a few areas .... the problem is to get that gain they have tested pure nitrogen against pure oxygen .... its your money, use it if you like

Jim

 

[NSTG8R]

Dang! You guys made me pull the spec. on tire inflation. Can't copy/paste as it's proprietary, and I like my job, but the general gist is:
No moisture - as I discussed earlier (altitude, expansion ratio, yada, yada...)
Non-corrosive to the wheel assy. - magnesium rims
Non-combustible - for 'braked' wheels.

Didn't think when I woke up this morning that I'd need to re-educate myself on "the use of nitrogen in aircraft systems"...but it's appreciated!

 

[Ty]

I had a guy argue "bigger molecules so they don't leak out as fast". Well, 78%of air is nitrogen. Fill the tire, wait, let the "bad stuff" leak out, refill that horrid 22% with regular air again and voila!, Your tire is now about 93% Nitrogen... one more time and it will be about 98% Nitrogen. Math is fun, right?

 

[skygazer6033]

I saw a new car window sticker which the dealer had added $199.00 to the price for nitrogen in the tires. Nitrogen is probably the cheapest industrial gas you can buy. It's been a long time but I seem to recall $15 or $20 for a 3000PSI bottle. Enough for probably 300 car tires. I asked the salesman if that included the spare and was assured that it did. That particular car didn't even have a spare. I walked! Anyway nitrogen is good but I really don't it's because it's nitrogen but because it's absolutely dry.