Decided to do a write up, I get so many PMs about my wheels. I'll use this to link it in the future.
The wheels are 19" Enkeis, not in production anymore. 8" wide up front, 9 1/2" out back. They were a metric offset, and not made for my car. So I had to measure for some adapters. Stock backspacing is 4" on an 8" rim. I ended up going with 2" billet adapters to get them to work. (The adapters have taken plenty of abuse and pretty intense amounts of hp/tq so yes they are strong. Don't care what anyone else says.)
The wheels in the back are very close to the trailing arm, and even closer to the sway bar. I didn't have to relocate the E-brake bracket on the TA but I did have to zip tie the cable to keep it off of the tire. If you go with a 10" wheel, you'll probably need to cut and reweld it. The rear wheels stick out a little more than stock, they're about flush with the edge of the fender. The front wheels are in a bit, just like stock.
If you're not going to run adapters then check with the guys on CF to find the max backspacing you can run. The safe thing to do, if memory serves was to run a 4 3/4" back space with a 9 1/2" wheel, allowing the wheel to stick 3/4" out past stock. You might be able to push it a bit more, not sure. I think the earlier C3s were somehow slightly different that the later C3s.
The tires are 235 35 up front, 275 30 out back. These are about 25.5" in diameter, stock is 27" My car is too low for a 27" tire, I have fender clearance issues with a 27" tire. If you decide to go with a smaller than stock diameter, make sure the car is low enough to keep the fender gap down. Good luck!