Nitrogen fills for street tires?

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I've read numerous posts, but wanted an update on folks' current thinking about the value of filling your FGT's tires with Nitrogen. Since most of us wear our tires out from the outside! rather than seeing rubber breakdown issues from the inside, how much value or gain accrues from bothering with Nitrogen? And how many think there are enough advantages to use Nitrogen in your daily driver (your Rolls)?

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[soroush]

nitrogen will provide consistent pressure in the tire in regards with temprature change.

 

[BlackICE]

nitrogen will provide consistent pressure in the tire in regards with temprature change.

Nope, Charles's Law

PV=nRT independent of the type of gas.

http://en.wikipedia.org/wiki/Charles's_law

Nitrogen's two possible advantages are that it is dryer than normally compressed air. When your tires heat up any water in the liquid state changing to water vapor will increase the pressure beyond what is expected based on Charles's Law. The second claim is it reduces oxydation of the tire from the inside. I doubt if that that matters. The O2, UV and ozone on the outside are much worst.

I think dry normal air is fine. The market for Nitrogen must of been thought of by an investment banker that could sell ice to Eskimos.

 

[JCSB]

Nope, Charles's Law

PV=nRT independent of the type of gas.

http://en.wikipedia.org/wiki/Charles's_law

Nitrogen's two possible advantages are that it is dryer than normally compressed air. When your tires heat up any water in the liquid state changing to water vapor will increase the pressure beyond what is expected based on Charles's Law. The second claim is it reduces oxydation of the tire from the inside. I doubt if that that matters. The O2, UV and ozone on the outside are much worst.

I think dry normal air is fine. The market for Nitrogen must of been thought of by an investment banker that could sell ice to Eskimos.

I think the actual argument is Nitrogen has a much larger molecular size than air and thus looses less pressure over time. I belive the claim to be 3-4 times better.

John

 

[S592R]

put nitrogen in all my cars. Bought a cylinder from airgas and regulator/ gauge about three years ago. seems like I don't have to air tires as often and they stay on pressure longer when sitting. As for the above post ..... pressure on track is slower to rise according to my logs.

 

[Beach-GT]

I think the actual argument is Nitrogen has a much larger molecular size than air and thus looses less pressure over time. I belive the claim to be 3-4 times better.

John

If that is the case, and air is around 90% nitrogen anyway, a couple of fillups will purge everything but the nitrogen that is left. Don't ya just hate physics?

 

[JCSB]

If that is the case, and air is around 90% nitrogen anyway, a couple of fillups will purge everything but the nitrogen that is left. Don't ya just hate physics?

Actually thats more like 78% and yes I love physics, studied it extensively in college. I personally use plain old air in my tires, but I do note that the FAA requires it for all commercial aircraft and most race teams use it exclusively. Must be snake oil. :willy

I would add that unless you own a nitrogen generator or have free access to one, then just regular checking of your air pressure should do just the same.

John

 

[Indy GT]

Air is Fine

I agree with BlackIce who is correct (as is usually the case).
Thanks for bringing Charles (Law) to the party.
IMO compressed air will work just fine.

Steve, there is no reason for nitrogen filled tires to respond to pressure changes due to thermal input any differently than air filled tires. With the slight exception (very minor indeed) of the water vapor contribution in the air filled tire. They both follows Charles Perfect Gas Law and both gasses will increase linearly with temperature (in Rankin) according to the PV=nRT gas law quoted by BlackIce.

I do, however, see some value in the larger molecule argument meaning the compressed nitrogen on the inside has more difficulty weeping out through the rubber structure and thus may maintain internal pressure longer than air. But a very small benefit IMO.

Save your money on this one (too).

 

[Specracer]

I use it. Couple reasons, one I have found it to be more stable on track in my race car. Yes it is moisture based. It is also consistent every time. You may get a crappy compressor with out a good air / water sep in some places, or worse a $.25 fill up at a gas station with out any water separation (like the GT supplied compressor).

One other reason, one might not think of, is a bottle of it in the trailer is easier than a compressor powered by a generator. You can even run air tools off it. When not racing I bring the bottle into the shop. If you just have to add a little air to something, it is easier, and faster, than firing the compressor.

 

[S592R]

I use it. Couple reasons, one I have found it to be more stable on track in my race car. Yes it is moisture based. It is also consistent every time. You may get a crappy compressor with out a good air / water sep in some places, or worse a $.25 fill up at a gas station with out any water separation (like the GT supplied compressor).

One other reason, one might not think of, is a bottle of it in the trailer is easier than a compressor powered by a generator. You can even run air tools off it. When not racing I bring the bottle into the shop. If you just have to add a little air to something, it is easier, and faster, than firing the compressor.

BINGO!

Indy I agree with your statements in the logical world .. but in observation I have found that Specracer is right on target out in the field.

 

[fjpikul]

Just so you physicists, chemists and engineers know:

Air = N2O5

 

[BlackICE]

Frank you forgot about the C02 that Gore is so concerned about. Also a lot of other trace gases in much smaller amounts.

 

[2006GT]

What is N2O5?

Representing air as N2O5 does not make sense. The approximate volumetric composition of dry air is nitrogen - 78%, oxygen - 21% and argon - 1%. Actually there are also trace amounts of many other gaseous components. The approximate mass ratios: nitrogen slightly greater than 75%, oxygen slightly greater than 23%, and argon about 1.5%. The molecule size of nitrogen theoretically is about 3% greater than that of oxygen.

The primary benefit of using nitrogen to inflate street tires probably derives from its reduced permeability, thus maintaining tire pressure longer. If one routinely checks and adjusts street tire pressures with air, there is probably no practical benefit in using nitrogen alone.

 

[Indy GT]

Nice post 2006GT ! And thanks for the numbers....

You have to cut Frank some slack though, he is only a physician and may have forgotten molecular representation of compounds with all the formaldehyde he has sniffed.

Steve, your comment is acknowledged, but other than just your "impression" of tire pressure stability there is no physics-based reason to justify the observation.

 

[timcantwell]

nitrogen will provide consistent pressure in the tire in regards with temprature change.

I use nitrogen at the track and also on the street if my bottle is full. It really has some, but not that great of an advantage. The big value is more consistancy in pressure across temperature ranges, but it also reduces the rate of oxidation for the alloy wheels and rubber. However, all these benefits are fairly negligible in the long run.

 

[S592R]

God Bless Tim Cantwell ... :lol

Indy.. thank you and I agree that the "physics" of it are dubious at best. However, I if not anything else am overly anal when it comes to obtaining, maintaining, and collecting data when I am at the track. My logs indicate that all four tires are more consistent under heat derived stress (aka driving the piss out of the car) under nitrogen (from the same source) than they are using the air source at the track (carried over in my carry tank). It probably has more to do with the "wetness" of the source air and that the source air in the compressor is varied in its production during the day ... ie temp, content etc than the nitrogen source which is solely constant. Now with that statement said .... I use nitrogen because I have the resouce, its easy, constant and that the tires "seem" to stay inflated at pressure for a longer duration. For going to the track and running HPDE ... I know that the pressure change is going to be a constant "X" for "Y" number of laps at "Z" temp. ... or moreover within a tighter box than with regular compressed air. So if it is nothing but mental comfort ... that is worth the $6 bucks it cost me to fill my tank which fills about 40 tires from flat to street pressure. IF I had to pay a shop $40 a tire to do it ... I'd run compressed air since like Tim said .. the overall is probably slight in the long run.