Can you replace a set of stock 18" wheels with 17"'ers?

I have a '05 CC w/out off-road pkg. and it has the 18" wheels and wanting to get some 17" wheels. Thought someone said it would mess with the brake calipers or something?

thanks

What tires are you planning to go with if you switch?

RudeBrewed has a set of 17" MD Razors that look sharp he's wanting to sell.