I second RePete.
Where are you getting them? Not unheard of to see offsets not on the spec list, but it is uncommon.
I'd just get the 7.5 +40 and 8.5 +40 if I didn't want to roll (which are on the spec list) or the 7.5 +30 and 8.5 +30 if I didn't mind rolling (also on the spec list).
Standard availability:
RAYS WHEELS