Why would anyone put anything larger on this car is beyond my comprehension (spelling?) if anything you would want to downsize the rear to an 18" that is unless you dig the whole 22" wagon wheel look.

If your looking to do a custom wheel set up, you might find it interesting to know that the Audi A4 have the same bolt pattern as the Crossfire, but they will require machining the hub larger and machining the bolt holes to be bolt centric and not hub centric.