Remember air already is 78% nitrogen, 21% oxygen, and 1% argon and other gases. Is pure nitrogen gas thicker than air? I doubt it (but don't quote me on it cuz my chem is a little rusty). A nitrogen gas molecule, with its triple bond, is smaller than a double bonded oxygen gas molecule so I doubt that nitrogen gas is thicker than air. Correct me if I am wrong?

 

No nitrogen molecules are thicker, almost 99% sure on that. That is why nitrogen tires keep their pressure persistancy longer than regular air filled tires.

-Sean

 

The main diff is that nitrogen filled tires are not as affected by heat as filtered air. Less expansion / contraction.

 

You can get some answers here: http://www.getnitrogen.org/

Apparently, some tire dealers will give you free nitrogen when you buy tires from them. Something you can look into.

I agree with the others though $40 is hefty price to get the same results. I'd try it, if it were free... after all, 40 bones is the price of a full tank!