It's a gimmick for the dealer to make an extra buck. Correct, our air is 78% nitrogen. There's no reason to put it in auto or motorcycle tires. I understand it is used in commercial airline tires but they run in sub zero air temperature.

 

I have been reading about nitrogen in tires for a couple of years in various magazines. I've neverread anything negative. Here's a link that tells the purported benefits:

http://loveyourtires.com/about_nitrogen.html

*Disclaimer: I have no idea if it's true or not !

 

dhoward has it correct. The only reason to use nitrogen in tires is if they use tire pressure monitors. If your car has tire pressure monitors and the outside temp turns cold the pressure in the tires will drop setting off the monitors. After you drive a while the heat will expand the tires. Nitrogen just keeps the pressure stable. No real advantage on a motorcycle.