Please do not fall for false ads.
Air is 78% nitrogen already.
The benefits of filling of your tires with nitrogen are similar to those of window tints that block UV rays (as if the glass wouldn't do it already).
The more entertaining version of this is here:
https://www.youtube.com/watch?v=eoCaoMRfv_o

 

Yeah I always questioned it myself, but it's what the TIA suggest as the superior method so we abide by it. Plus we do it for free where a stealership would charge you like $50 to fill up.

 

Tire Rack's Write up of nitrogen

Pretty much this

 

I monitor and add air to my tires too much to fool with Nitrogen

 

mine came with nitrogen. some package that was added to my car. I wonder if i switch out my rims, if i can get them add nitrogen and keep the "warranty" that came with the nitrogen package.