Appropriate Wheel Offset for 18" Wheels?

Oops! Forgot to say stock 7-1/4 with 1.5" conversion spacers. No rubbing with the tired stock leafs, just put some hotchkis units in and haven't really pushed it yet. Normal street driving and no issues so far. No mods other than the spacers.

I have to measure my hub-to-hub distance for an 8-3/4, I'll let you know what i get.