Death2000, Good question...I'll find out about the offset. Turns out these wheels are the very same type, I have been looking at. http://www.carid.com/ruff-racing-wheels/r281-92216.html
Only by a different seller. He has 4-18x8.5's but not the 74.1 hub bore.
The e39 tire link is a good one but it only addresses the standard sizes.
I just worry that the 18x9.5 will rub something terrible or worse yet.. vibrate the front-end to pieces!