Nitrogen does nothing for performance, I havent had to put air in my tire for about 1 year so regular air is just fine. Does nitrogen weigh less than air? I know if you take a deflated tire and weight it, then fill it up to 35psi with aire you will gain about 2lbs.

I think race teams use the nitrogen because you don't need to haul around a compressor when you have 3000psi tank so you can run air tools with.