Nitrogen for tires?

[jerry33]

I run nitrogen in my tires and they definitely maintain proper inflation longer than when I use compressed air. Here is a scholarly paper on the subject... http://www.getnitrogen.org/pdf/graham.pdf explaining the scientific principles. The conclusion reads...

"O2 permeates faster through rubber than does N2 and a major aspect of why it is a good idea to significantly reduce the amount of O2 used to fill tires by replacing most of the O2 in air with enriched N2. Since N2 permeates through the tire rubber more slowly than would O2, using enriched nitrogen instead of air for tire filling contributes to better maintenance of the proper inflation pressure for the tire."​

That was certainly true in 1950. However, during the 1960s, butyl started to be commonly used for tubes and tubeless liners. Butyl is oxygen tight. Of course, if the liner or tube has been damaged it will lose air slowly, and a slightly faster with air until you evacuate the oxygen by regular top ups (of course there will be other damage down the road). So the article is correct--just a bit out of date.

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If that is correct, your tires would approach 100% Nitrogen over time.
If you start with 80% Nitrogen and20% Oxygen, and you are losing Oxygen preferentially, your Nitrogen concentration increases. Even after adding with 80% N2 and 20% O2, your N2 concentration is higher than air. Or am I missing something?

You're not missing a thing. That was standard practice in the 1950s.

 

[richkae]

The last time I bought a new car there was a line item for $100 for Nitrogen filled tires.

I think that line item actually meant "we thought of an excuse to charge you an extra $100"

 

[ecarfan]

I run nitrogen in my tires and they definitely maintain proper inflation longer than when I use compressed air.

In my experience, modern tires maintain their pressure on air for months. I am not interested in paying even an extra penny for nitrogen if all it accomplishes is that I will only have to check my tire pressures annually, let's say.

Modern cars with TPMS will alert you when your pressure is low. Maintaining tire pressures is pretty easy using regular "free" air. But I'm sure the nitrogen suppliers want to convince you that their gas is "better".

 

[jerry33]

In my experience, modern tires maintain their pressure on air for months. I am not interested in paying even an extra penny for nitrogen if all it accomplishes is that I will only have to check my tire pressures annually, let's say.

If you only check your tire pressure once a year, you don't know what pressure they are at. Nitrogen changes with temperature exactly the same way that air does. There will be zero difference if the air is dry.

 

[LineofSight]

I fill my tires with helium. It reduces the unsprung weight.

 

[Chipper]

I fill my tires with helium. It reduces the unsprung weight.

Yes...but it makes your car sound funny when it is talking to you.

 

[sandpiper]

I fill my tires with helium. It reduces the unsprung weight.

You should go with hydrogen. It's even lighter and as an added bonus it might make a simple tire blowout on a deep pothole exciting.