This is a great tire size calculator I've used in the past. Gives you everything you need to compare tire sizes.
http://www.1010tires.com/tiresizecalculator.asp
If you don't want to spend a whole lot, the Ventus V12's is a pretty common choice. I don't know a whole lot about its tread life, but its inexpensive enough to not worry about it. As with most high performance summer tires, the compounds used are usually softer and wear a lot faster. If you want something that will last longer, you should probably look into all-season tires which have harder compounds. You won't be setting any record breaking lap times, but they will last longer. The stock Potenza's aren't
that bad, but they do get really noisy once they wear out. You're not gonna find a tire with better performance
and better thread life. It's one or the other.