Luke---Please help 18" wheels
I got my figures this way:
9.5x18 ET31 vs. 8.5x18 ET31: 1" difference in width, same offset. As offset is a measurement relative to the center line of the wheel, and the 8.5" width wheel is 1" narrower than a 9.5" wheel, running non staggered will sit 0.5" more inward.
9.5x18 ET31 vs, 8.5x18 ET35: Will sit 4mm more inward than 8.5x18 ET31. 8.5x18 ET31 in the rear sits 0.5" more inward than the rear wheels in the picture. 4mm = 0.16". 0.5" (9.5x18 ET31 vs. 8.5x18 ET31) + 0.16" ( 8.5x18 ET31 vs. 8.5x18 ET35) = 0.66" (where 8.5x18 ET35 will sit compared to the rear wheel in the picture)



