JRoc

I own a 2008 Saab 9-3 Aero and I'm thinking about getting the Konig "Unknown" wheels. But what size tire should I go with? The 225/45R-18, 235/40R-18, or 245/40R-18. Another question I have is. Are there alot of Saabs out there with the wheel I'm thinking about getting? I'm going back to the states soon and I don't want to see every other saab with the same wheel as mine. Is that understandable?