I'm really looking for guidance with the tire size, wheel width and offset.

Will the +30mm or +38mm offset work upfront on the 9" rim on either the 245/40 or the 255/40 18's?

Will the +45mm or +42mm offset work in back with the 60.5" flange to flange (With the disc brakes) '68-70 B-Body rear-end in a Duster with the Dr Diff 1/2" offset spring hangers and shackles?

I prefer not to run spacers and I plan to have full size spare tire from the front that I can install with each combination.

The height on the 245/275 combination is (25.7"/25.6")

The height on the 255/285 combination is (26"/25.9")

I really don't want to go any wider than this.