proper offset for rims

Do want to go staggered or keep them the same front and back?
The offsets in the 20mm range will keep them near the same as the stockers. The offsets in the 30mm range will put a 8-9" wheel near the edge of the fender on the front and slightly tucked under the rear. The offset in the 40mm range is best suited for the 10" wheels on the rear which puts it even with the fender.