Use this chart to figure out the optimal wheel and tire size you're going for:
You can also download a copy of the original spreadsheet with formulas to try out your own combinations by right-clicking here and saving the file to disk.
-Ed
EDIT: Fixed error in comments at the bottom from piggybacking off a chart for a different car.

You can also download a copy of the original spreadsheet with formulas to try out your own combinations by right-clicking here and saving the file to disk.
-Ed
EDIT: Fixed error in comments at the bottom from piggybacking off a chart for a different car.