This thread will go on and on then likely end like the last one.
Total waste of money.
The idea started in the Space Shuttle program as "safety gone wild" on the idea that if there was no oxygen to contribute to a fire "it would be safer". Additionally, when the tire exploded; the inert Nitrogen would "put out the fire." (Space Happy Lunacy - pardon the pun)
Spread to the aviation community by Safety Officer's chatting it up and then to racing; since if it was good enough for Space and aircraft it had to be good.
Not to miss a beat to make money, waste gas from the Liquid Gas company's separation process to get Helium, Oxygen, Argon and other "money" gasses; Nitrogen used to be vented to the atmosphere.
Once there was a small market, they started pushing it to gas stations who added 5 dollars per tire sold as almost pure profit. The Nitrogen was costing them about a nickle per tire.
Marketing came up with the ludicrous idea that even though N was ONE SPOT to the left of O on the periodic table; O2 is somehow smaller and could somehow "slip" through smaller holes in rubber. 1 proton and 1 electron less will not make anything smaller in any significant way. In fact since the missing electron is in the same "shell" as the oxygen electron, the "size" is actually the same. Also, there are TWO atoms in each molecule of gas. So, bound together the inter-atom distance is also the same since "shell" to "shell" distance is the same.
TOTAL BS marketing.
Dynamic Periodic Table
So belly up to the table (periodic - sorry could not help myself); and plop down your hard earned cash.
Oh, as the word got out that it was useless, most tire stores now offer it for free as a " service" to their customers since no one would actually pay for it anymore. They can still use it as a CHEAP marketing ploy to get you to buy their tires.
Can we put this to bed? Probably not. This idea is more closely held by some folks than.... well anything. Someone will jump on with how having Nitrogen filled tires saved a small child in a burning wreck by exploding and putting out the fire. Just wait and see.