Has anyone on the forum went to a 20" wheel on their dually? If so, what's your opinion and how much did this lower your rpm at highway speeds?

 

Wheel size does not affect rpm. It is the tire size you have mounted regardless of rim size. You can get the same effect by increasing the circumference of the tire on stock wheel. The problem with larger tires on a drw is the bulge and possible rubbing when load on the rear tires.

BTW, the Ford drw wheels are 19.5" not 20". The standard tire on the 2015 was 225/70Rx19.5G.

 

Thanks for responding but maybe my question wasn't stated clear enough. I have a 2016 KR F350 with stock 17" rims and don't like the looks of the setup since IMO there's too much open wheel well showing. Plus I like the tire options better in the 20" rather than the 19.5".

 

You would have to go with a 35 or 37 inch tire to fill up some of the wheelwell openings. Then a whole new can of worms opens up!