It's not my site but is very accurate. Although, my SC didn't come with cruise. This link is specific to the 16's and has notes on the 15's. I have 15's on mine but have a hard time finding 225/50 and 205/55 series tires. I got the last pair in the warehouse when I needed to replace the rear tires. 16's may have better luck.
16" Fuchs Wheels - Porsche 911SC Special Weissach Edition