Haha, nitrogen in tires is a fantastic scam. As they say, a fool and his money are soon parted. Consider that you would have to produce an absolute vacuum inside the tire before pumping in the nitrogen to remove all ambient air - and of course, the tire bead can't hold up to an absolute vacuum so unless you're running tubetype tires, you'll never get all the oxygen out.
The many and various myths of nitrogen I've heard on motorcycle forums:
- nitrogen, having bigger atoms, will leak out more slowly (technically true, but insignificantly different - N has a Van der Waals radius of 155.pm vs. O's of 152.pm)
- nitrogen is more stable across temperature ranges and so won't vary as much as temps drop (true, but only marginally so - and how do you top it off when it *does* drop if you can't use a regular pump?)
- oxygen on the inside of the tire will oxidize the rubber and shorten the tire life (this is my favorite purported benefit because it would only be true if you got every last oxygen atom out of the tire)
- nitrogen makes the tires lighter and reduces weight (I think this one is really funny - though nitrogen *is* slightly lighter than oxygen, the weight difference is tiny even before considering that ambient air is already 78% nitrogen. Factor in that the air in tires is pressurized to the same pressure regardless, and any weight difference should be negated by the higher number of nitrogen molecules present at the same pressure)
Now, there *are* reasons that airplanes and race cars fill their tires with nitrogen - most notably, the fact that nitrogen is just about completely inert. That property means a couple things - more dependable wear for the tires, and removal of the fear that it might fuel fires and explosions the same way that unknown environmental gases might. But airplanes and race cars exist at the very envelope of what we can design for, and every last bit of safety and performance can be worthwhile.
But seriously, I think fools being sure that their family van needs nitrogen in the tires probably makes them *less* safe, and here's why: how many of you have a nitrogen tank in your garage? Now, how many of you have a bicycle pump? If you notice your tires are a little low, you can grab the bicycle pump and fill them back up; but if you've just spent $5 on nitrogen and notice it's a little low, you're more likely to drive around on that less-inflated tire for a while before shelling out money to top it off, which means you're driving in a less-safe manner in the mean time. Of course, if you *do* spend money on nitrogen, but top it off with a bicycle pump when it's low, you're losing any supposed benefit you might get.
And besides, back to my original point, if they don't start with an absolute vacuum inside that tire, you're going to have oxygen in there. And there's no way you'll get a tubeless tire to seat in an absolute vacuum. So you're going to have oxygen in there.
It turns out that oftentimes when people purport to being "sick" but there's no medical explanation why, prescribing a placebo will cure the illness. I think nitrogen in tires is exactly that placebo for car enthusiasts.
