Looking at OEM 2012-up Focus wheels I'm guessing? 55 will be too high for an MN-12, 40 is more like it on an 8" wheel. So with 1/2" spacers they would be OK, but you may not have enough stud length for proper thread engagement ... you would have to test that, since it varies with the thickness of the wheel centre in the stud hole area.
cheers
Ed