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My tyres were filled with nitrogen on my Elise when I last put a new set on. I still check pressures every week and haven't noticed any difference between now and when their was air in the tyres (the theory that they loose pressure slower than air filled tyres is pretty shaky). Can't comment on the pressure changes as I haven't tracked it with nitrogen only.

Bottom line though is that for road use I wouldn't (and didn't) pay extra for nitrogen.
 

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Ticket Magnet
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I thought this might be pertinent to your question.
Nitrogen will expand less than air when heated and thus is better as a tire pressure regulator for tires that heat-cycle. The main reason for this is water vapor - humidity. Besides the fact that it just expand more and therefor gives a much greater spread form cool to hot, different air contains different amounts of humidity from day-to-day, morning to afternoon and so on. You are always trying to guess what the hot pressure will be when using cold pressures to set hot ones.

http://www.getnitrogen.org/pdf/graham.pdf
 

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Ticket Magnet
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They are using a controlled gas with zero humidity. CO2 is a molecule that is much larger than single Hydrogen atoms so it permeates through membranes slower.

I wonder if she could help me inflate something?
 

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I use Helium. It makes the car lighter.
 

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I use nitrogen. It is exactly like R4Racin said, pressures are easier to predict.
 

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I use the following mix:

Nitrogen 78.08%
Oxygen 20.95%
Argon 0.93%
Carbon dioxide 0.03%
Neon 0.0018%
Helium 0.0005%
Krypton 0.0001%
Xenon 0.00001%
That's why you're missing out on all the available Lotus performance - no flourine, chlorine, bromine, or radon!! rotfl
 

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I use the following mix:

Nitrogen 78.08%
Oxygen 20.95%
Argon 0.93%
Carbon dioxide 0.03%
Neon 0.0018%
Helium 0.0005%
Krypton 0.0001%
Xenon 0.00001%
How did you get all the water vapor out. It is by far the thing that contributes to pressure differences do to temperature. I imagine if you have a very, very good dryer system in line after your air compressor your tires pressures would be practically almost as stable as nitrogen. In fact nitrogen is used for stability mostly because the equipment used to put it into the containers we get it from is equipped with very, very good dryers.

Sent from my SPH-D710 using AutoGuide.Com Free App
 

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My buddy Jeremy fills up with nitrogen at the track and loves it because his tire pressures remain constant across the temperature range.

He comes to the track with a pressurized container of nitrogen and fills and empties the tires twice to dilute any residual water vapor.
 

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Good idea. I suspect if you mount your tires in the Sahara dessert and then purge and refill them several times with either nitrogen or very well dried air that you might actually get the humidity in them down to ten percent or so.

I just adjust my pressures a few times during a track day and figure it's less effort.
 

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Come on. 10% should not be difficult to get. Here are the current conditions here in Colorado.
 

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I use:

Nitrogen: 20–90%
Hydrogen: 0–50%
Carbon dioxide: 10–30%
Oxygen: 0–10%
Methane: 0–10%

And I use a Flatus pump.
 

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I thought this might be pertinent to your question.
Nitrogen will expand less than air when heated and thus is better as a tire pressure regulator for tires that heat-cycle. The main reason for this is water vapor - humidity. Besides the fact that it just expand more and therefor gives a much greater spread form cool to hot, different air contains different amounts of humidity from day-to-day, morning to afternoon and so on. You are always trying to guess what the hot pressure will be when using cold pressures to set hot ones.

http://www.getnitrogen.org/pdf/graham.pdf
The humidity in the air pretty much condenses in the bottom of the compressor tank. The air that comes out of a compressor is relatively dry.
 

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My buddy Jeremy fills up with nitrogen at the track and loves it because his tire pressures remain constant across the temperature range.
Um...PV=nRT for air and pure nitrogen. His tire pressures do not remain constant across the temperature range unless he is somehow able to defy the laws of physics.
 

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I tried nitrogen in my race car for a year or so, going on the theory that the tire pressures would not change as much with temperature due to the lack of water vapor.

In practice there was no difference, so I just use compressed air now. I've run the same tires long enough on the same car that I can set cold pressures and get the hots to come out within 0.5 psi.
 

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I tried nitrogen in my race car for a year or so, going on the theory that the tire pressures would not change as much with temperature due to the lack of water vapor.

In practice there was no difference, so I just use compressed air now. I've run the same tires long enough on the same car that I can set cold pressures and get the hots to come out within 0.5 psi.
What he said.
Even a Dyson tech said it is great at a track but useless on the street. They just pull the valvestems, deflate and refill with Nitrogen for true racing. That results in 99+ % of the outside "air" being gone. I'd like to try it because tires that pick up 6-8psi during a session are a handful at times.
 
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