We've tested both the 8.5" and 9" wheel on the front.  Tire sizes weren't optimal for testing, but they gave us useful information. 235/40/18 NT-05 was used on the 8.5" wheel and 245/40/18 was used on the 9" wheel.  Both of these sizes are significantly taller then stock.

245/35/18 is the recommended front tire size if camber plates are installed.  Without plates 225/40/18 is recommended.