I agree wholeheartedly that the lack of basic scientific knowledge in the general population is a tragedy. Although there could be EXTREME conditions recommending use of nitrogen, these don’t occur in cars. One claim in particular: your tire won’t lose pressure as fast. Unless you’re filling with helium, this shouldn’t be a problem. Even if it were true, stop and think. With air containing 80% N2, the tire supposedly leaks mainly O2 so you’re now up to 90% N2. Top off the tire with air and your’e replacing that lost O2 with 80%N2. After topping it off a few times, even if this were true, you’d end up with higher than 95% N2 anyway.
Be careful how you throw this stone. Scientific knowledge isn’t all that universal. If I may illustrate the point:
Most pressure loss occurs between the rim and the tire, not through the tire.
Also, the Partial Pressure Law of Gases works for tires as well. Example: If you have a tire filled with pure nitrogen, oxygen will leak back into the chamber. Put another way, you don’t wind up with a high concentration of N2 when you start with air - at least at the pressures used in car tires.
BTW, did you know that airplane tires are sometimes inflated to over 300 psi? So when traveling at 30,000 feet, the difference in pressure can almost be ignored.
After seeing these posts – I wonder about the Nitrogen that is in my tires. I have a 2007 Volvo XC90 that had issues with the tires leaking air ever since I bought it. I even had to replace two tires due to uneven wear. Then I finally gave in to the dealer and paid them to put nitrogen in the tires. Since the Nitrogen was put it – I haven’t had any issues with the leaking air or my tires.
Stacy
Stacy, if you could eliminate all the other possible causes for the problem, I would be more likely to believe it was the Oxygen that caused the problem. It could be that you had defective valve stems installed initially, and it could just be coincidence. It could also be that your previous tires didn’t seal properly with your rims. Assuming it was the Nitrogen that fixed your problem without eliminating other possible factors that could have been coincidentally fixed is a leap of faith.
Nitrogen might be great for inflating basketballs and footballs. Apparently, it doesn’t migrate through the rubber as air does and the basketballs and footballs would maintain pressure better than if inflated with air.
See, I just don’t get the ‘nitrogen migrates less than air’ idea. Air’s 78% nitrogen, after all, so it’s almost the same stuff. Oxygen’s actually a heavier molecule than nitrogen, maybe a tiny bit smaller in size. I’d like to see some actual data to support the claim.
Stacy:
I agree with Whitey’s thinking.
I don’t believe it was the oxygen in the tire air that caused your tires to leak. It was likely something else. Perhaps they cleaned up and sealed the rim bead surface when you got new tires. Or as Whitey noted, it could have been your valve stem(s).
Now this is interesting. I’ve always been curious as to the leakage rates of various molecules through butyl rubber since this nitrogen cra… I mean stuff started. According to this- http://www.velonews.com/article/87175, it appears as though oxygen is less likely to permeate than nitrogen. I’d be interested in your opinion.
snip
Butyl rubber dominates the market and is used for almost all tubeless tires and bike tubes as its permeability to air is incredibly low ? butyl tubes have only 10 percent the leakage rates of natural latex rubber tubes.
Permeation by diffusion predicts gas leakage rates proportional to the inverse of the square root of their molecular weights. Using air as a reference the predicted leakage rates for common gases are: helium 2.7, air 1.0, nitrogen 1.02, oxygen 0.95, argon 0.85, carbon dioxide 0.81.
It turns out however that the leakage rate of CO2 is huge, and the reason is that it is actually soluble in butyl rubber and is thus not constrained to normal permeation loss, it can transfer straight through the bulk rubber resulting in severe tire pressure loss on the order of a single day.
end snip
Maybe we could fill a bowling ball with nitrogen to test this theory.
www.carbibles.com has a great primer on wheels and tires with an excellent discusison of air vs. nitrogen. I recommend a visit.
The only oversight I noticed on the site was that in their discussion on nitrogen use by racers they didn’t mention the safety reason…nitrogen will not feed a fire in the pits like compressed air would.
I posted this earlier in the thread-
Now this is interesting. I’ve always been curious as to the leakage rates of various molecules through butyl rubber since this nitrogen cra… I mean stuff started. According to this- http://www.velonews.com/article/87175, it appears as though oxygen is less likely to permeate than nitrogen! Perhaps I’m reading it wrong. I’d be interested in your opinion.
snip
Butyl rubber dominates the market and is used for almost all tubeless tires and bike tubes as its permeability to air is incredibly low ? butyl tubes have only 10 percent the leakage rates of natural latex rubber tubes.
Permeation by diffusion predicts gas leakage rates proportional to the inverse of the square root of their molecular weights. Using air as a reference the predicted leakage rates for common gases are: helium 2.7, air 1.0, nitrogen 1.02, oxygen 0.95, argon 0.85, carbon dioxide 0.81.
It turns out however that the leakage rate of CO2 is huge, and the reason is that it is actually soluble in butyl rubber and is thus not constrained to normal permeation loss, it can transfer straight through the bulk rubber resulting in severe tire pressure loss on the order of a single day.
end snip
Once before I threatened to do some testing to check this theory out. Now I think I may have to follow through. I have access to various equipment that can measure atmospheric gases down to the ppm. I also have access to supplies of 99.9% pure nitrogen and oxygen. I think I’ll evacuate a bike innertube (the butyl rubber type to mimic a car tire’s inner liner) and fill it with nitrogen. Then test it every so often to see how it equilibrates. Then repeat the test with pure oxygen to see how fast nitrogen permeates and equilibrates. I just need to find the time…
Is that so? Too bad there is no way to prove it!
Paying $39.95 to have your four tires filled with nitrogen is for suckers!
“Is that so? Too bad there is no way to prove it!
Paying $39.95 to have your four tires filled with nitrogen is for suckers!”
Who is your comment addressed to?