Appropriate Wheel Offset for 18" Wheels?

Peter gives his wheel specs in this thread, I told you would not need more than a 1/2" spacer in the rear. http://www.forabodiesonly.com/mopar/showthread.php?t=136761&page=3
I'll look it over. I'm looking through the site Tomwheels recommended to see if I have different options: http://www.americanmuscle.com/18inchwheels.html

Edit: Looked it over and it seems like he had the perches moved in allowing him to run about +24mm offset in the rear. Just an observation. I'm also looking on Summit for wheels I like and trying to see if I can find a wheel with two different offsets.