I'm actually running an '07 Boxster that came with the facotry option Caymen 18's...thanks for all the help guys, it's starting to sound like picking up a set of used factory rims might be my best option - hopefully craigslist will have a cheap set.

-the NWR SCCA region that I run in has a street tire indexed class (same rules apply for all classes, but only street tires)...I'm planning to run that next year. (I'm currently running a '05 350Z in BSP...touting a tire trailer, changing wheels, rough suspension, loud exhaust and expensive tires are starting to pay it's toll on me - I'm looking forward to autoXing the Boxster on street tires!