By that theory the super stripped down Pro also has the same base with 18's.Right, but EPA rating is not based on every possible option combination. My theory is that the EPA ratings are based on trim before options, hence lower range for Platinum. It could be wheels but I've never seen an ICE vehicle with a lower EPA mpg because of wheels. I could be wrong.
Yet the Plati is fat with extra equipment, 22's and reduced bed haul capacity, because she's a fattie, I believe the rolling diameter of 20 & 22's are similar if only fractionally different, easy calibration in the ECM.
Sponsored