By Roger Marble
Regarding nitrogen (N2) passing through (permeating) tire rubber more slowly than oxygen (O2) due to molecular size, are nitrogen molecules really larger than oxygen molecules? According to the Get Nitrogen Institute in their paper on N2 effusion,”The correct answer, with respect to ‘permeation,’ is yes.”
So I imagine your question is: Why don’t I support the effort to “sell” the idea of always inflating your tires with just nitrogen? It comes down to effort and cost versus level of benefit.
Maybe one way to think of this would be to imagine dropping a penny as you walk away from making a small purchase at a store. If you dropped a number of coins you might stop, bend over and pick them all up. But what if you only dropped one penny and didn’t discover the fact until you had walked to your car. Would you walk the 20 feet back to the store to look for the penny? I bet not. There is no doubt that you would have more money if you picked up the penny, but would you consider it worth the effort?
In general, tires lose about 1% of their inflation pressure each month in laboratory testing. This is almost entirely oxygen. It is also true that tire pressure changes about 2% for every change in temperature of 10° F. This is true for nitrogen or air.
I haven’t tried to run a test, but it is also true that every time you use a hand pressure gauge to check your air you let a little air out. How much air do you let out if you use a gauge to check your tires every day? Might it be 1% in a month’s time? Might it be more?
Finally, what does it cost to inflate your tires with N2? Even if you have a deal with a dealer and can get your pressure “topped off” for free, you still have to drive to the store location to get that “free” inflation.
IMO, the small level of benefit of inflating tires with N2 just isn’t worth the effort and cost. There is also the real negative of not checking your tire pressure simply because you believe that by inflating with N2 your tires will never lose pressure so you don’t need to check. What about small punctures or leaking valves? If you don’t check the pressure you will not learn about the leak until it is too late.
However, if you want to inflate your tires with N2, I see nothing wrong with doing that. After all, it’s your time and money, not mine.
Have a tire question? Sign up for Roger Marble’s new Facebook Group: RV tire news, information and discussion, hosted by RVtravel.com and moderated by Roger. He’ll be happy to help you.