Ok, So I just got my car aligned today and while I was at Acura I noticed they provide this service now where they fill your tires with nitrogen because it supposdly can give you better gas mileage since nitrogen weighs less than air. Now I am not to surprised from this because I know first hand that the military and airlines use nitrogen to fill their tires. But could this really be beneficial to improve gas mileage. What's everyones opinion on this?

 

I have nitrogen in my tires. Doesn't make a difference on gas mileage but does appear to help maintain tire pressure a lot better. Also most tire places will not touch your tires if they do not have the capabilities of providing nitrogen and your valve stem caps are green (green for nitrogen). So if you need to fix a flat your S.O.L. Have to take it to someone that does.

 

I think it's less about the weight of the gas and more about the nitrogen being less affected by temperature, thereby keeping your tire pressure more consistent, thereby improving mileage. I know using nitrogen in cart racing has been going on for many years, since their tire pressure is critical with such low pressures....+/-1 p.s.i. makes a BIG difference with how their carts handle. Somebody chime in if I'm way off base on this one.

I think you can just fill with air if you have a tire issue.......you'll just need to have the tire recharged with nitrogen after the tire gets repaired.

 

Nitrogen does not weigh less than air. Air is 78% Nitrogen and 22% oxygen (or something like that). The density difference between N2 and 02 is < 0.15 grams per litre at 0 degrees C.

The benefit from using nitrogen in your tires, is that there won't be any water vapor in the tires. All gases expand and contract with temperature the same, because of pv=Nrt. Water vapor on the other hand, is different, because it also goes through a phase change from gas to liquid and back. That's the main reason you want dry air in your tires. Water Vapor can expand/contract dramatically with temperature change, becuase of the phase change.

However, you can achieve 99% of the same benefit by installing an in-line line dryer on the air-compressor, so that the air is moisture free. That's what I did on my air compressor. (The line dryer is < $20 at home depot)

 

That's all very interesting though it's kind of a shame that if you get your tires filled with nitrogen it's hard to find someone to service them if you get a flat. So do you all think this is going to be a widely spread thing. Maybe a standard soon?

 

it is pure profit for them

 

Unlikely. I think it's a fad. People hear things like "cart racing does it" and they assume it must make your car go faster or something good that you want to have happen to your car, even if you don't really know what it is or why it works. Kind of like people who use premium gas in a car that dosnt use it, because "more expensive must be better"

 

Due to the severe and extreme temps that race cars tires, airplane tires and the military experience on a daily basis- use of nitrogen to control the temp is a major advantage to them.
For the general public- its a great money maker for the installing facility, and ensures your return for everything- since they have the stuff if you tire gets low.

If you have a flat and need it fixed- all the stuff is gone from inside from the leak, so any shop can do a repair or tire replacement for you. It may only get air filled at the time, and then you go to your place for a drying out and fill with Nitrogen.

If its free, and you are not in the habit of checking the tire pressures once a month or more, then its handy to have.

 

I just had nitrogen put in my 2007 TLS at the dealer. I live in Florida and we're at the time of year when the temperature fluctuates more than usual. This causes my tire pressure indicator to go off several times a day. The nitrogen is supposed to prevent this and so far has. (Only 2 days so far)

I have 2 weeks of "data" from my trip computer prior to the nitrogen. I reset it right after the nitrogen was put in. I'll compare the next two weeks or so and let everyone know if the gas mileage improves. It won't exactly be a scientific study, but may give us an idea if there is any measurable difference.

 

Some of the stuff about servicing nitrogen filled tires in this thread are incorrect.

Got the nitrogen fill free with my '08 Ford Expedition EL as an incentive to buy. Anyone can service the tires & you can add regular air at any time if you need to.

When you have a chance you can bring it back into the dealer. They will purge the tire & refill with nitrogen free of charge.

We run it off road & I got a flat which was repaired where we were. Had the tire re-inflated with nitrogen at the local Foed dealer during a lunch break.

I have about 5,000 miles on the EL & so far the TPMS has not shown any change in pressure.

No idea about fuel savings but if that was at the top of my list I would not have bought a 6,000lb truck.

 

The fuel savings comes in as your tires do not lose as much air, maintaining the optimal tire pressure. Running underinflated tires (which alot of the general public probably is rolling on underinflated tires) decreases gas mileage and causes additional wear on tires, which is where the fuel savings comes into play.

Just check your tire pressure with a gauge every week, and your golden, at least thats what I do

 

This ^^^^^ a very throughout and correct answer. No reason to run nitrogen over a compressor with a good moisture trap.

 

Agreed. I tried nitrogen for a year because it was free and now that I've been back on normal air I haven't seen a difference in pressure fluctuations. It's just a way of taking your money.

 

At the end of two weeks, my car is getting approximately 5% better mileage. I believe it because the pressure in the tires is very stable. Also, the tire pressure indicator hasn't gone off in two weeks. I'm pretty happy.

 

You get the exact same effect of having your tires filled with air from a compressor with a drier in line. Any gains are going to be from less moisture in the tire, not the nitrogen.

 

The Federal Aviation Administration (FAA) requires nitrogen in all commercial aircraft tires.

Regulatory agencies require the use of nitrogen when inflating tires for aircraft above a specified Maximum Takeoff Weight (MTOW).

Michelin recommends the use of nitrogen when inflating all aircraft tires. Nitrogen provides a stable, inert inflation gas while eliminating the introduction of moisture into the tire cavity.

Aircraft operating procedures for initial inflation and adjustments must comply with applicable instructions as given in FAR 25 or JAR 25.

U.S. Government – NASA and the U.S. military use nitrogen for many of the same reasons it used in commercial aircraft.

 

And you know the reason? Large temperature fluctuations. People use it in race cars too where there is enough heat in the tire to make setting pressures a problem with plain old air. Moisture in the air is the primary reason why it makes any difference. There isn't really anything special about nitrogen otherwise. As stated before, using compressed air with a good moisture trap will give you the same effect as nitrogen in any normal situation. The only nice thing is that as a refined, bottled gas nitrogen wont contain any moisture. For a street car? Check your pressure once a month and don't worry about it. (You should be doing that anyways.)

 

Just stating a series of facts not which is better for a car. This can be just like the oil/oil filter debate of how much over spec is required.

As for drying the air I have filters & moisture traps on my compressor at home but wonder how many or what quality the filters/traps are at the drop in 25 cents to fill units at the local gas station sites.

BTW to insure that moisture is kept to a minimum in aircraft tires the FAA states that no more then 5% oxygen is allowable. This allows for top offs where nitrogen is not available.

For my own personal use ,right now my Expedition has nitrogen fill while my other cars & trucks do not.

 

Probably pretty crappy ones I imagine. If you're really worried about dry air, fill your tires off a scuba tank. Its about the driest air you'll find.

 

My gear is set up to spray paint so I don't really have anything to worry about regarding the air quality for my tires.

 

I'm a new member to the 'Zine and have just read these series of comments. I am in Ontario and this is the first winter I am going into with my '08 TL. As the temperature has been nearing the freezing point overnight, I am regularly seeing my tire pressure warning come on most mornings. By the time I have gone half way to work, it seems to have warmed up the tire area, and the warning light goes off. It's a little annoying, but I am worried that I won't pay attention when I REALLY have a pressure problem.

 

Simple solution: put in air up to the recommended pressure when your TL's tires are COLD (or put in air, then adjust to recommended pressure first thing in the morning).
Your TPMS warning thereafter should come on only when there is a problem.

Welcome to AZ!