Nice job on the stance. Perfect! I'm trying to get BFG 255/60R15's in Canada but they're backordered at least for 2 mths if not more. You seemed to get yours pretty quick....are they from Newstalgia Wheels??
Kris
Your first line of thinking is correct. The second will push the wheel out too far. Check this wheel size comparer out. It works great.
http://www.rims-n-tires.com/rt_specs.jsp