QUOTE(Jetsetsurfshop @ Nov 10 2013, 08:23 PM)
I have a few sets of wheels and wondered if theres any reason I would need two different tire sizes? I currently running 205/50/15, think I need 215/60s? Would this be beneficial at a larger track like Sebring?
Get a spreadsheet with a gear chart.
Add in tire diameter
Add in your optimal RPM where you make peak power
You should be able to plot the tire diameter or gearing that will provide you with what you need.