Okay... Here is the official/unofficial stance on offsets. (by my expensive personal experience)
I no longer recommend anything over 0mm offset, unless you are using your Raptor as a show truck or full time street queen. I am running -12mm offset (until next weekend) which requires being on top perch. In 16,720 miles because of negative offset wheels I have had to replace:
2 cv axles (not covered under warranty)
2 hub/wheel bearings (not covered under warranty)
A handful of stupid plastic fender clips
4 goodyear duratracs (due to wheel/hub bearings and alignment issues)
4 alignments
So I ONLY recommend 0mm - +34mm offset wheels.
Yes, I am eating crow because I was a strong supporter of negative offset wheels.
-Greg