Has anyone here downsized from the OEM 20" wheels back down to the OEM size 17" wheels and tires? Any change in fuel economy? Better or worse?

I made an interesting discovery about my truck today. It came with the Lonestar package that included the 20" OEM wheel upgrade. However, I don't think Dodge reprogrammed the ODO for the change in wheel diameter.

20" wheel with 275/70 R20 tires has a 33.0" overall height.

All Dodge 1500 4x4's are spec'd from the factory with a standard tire wheel size of 265/70 R17 with a 31.5" overall height.

After driving the same route with two different trucks, checking the google and mapquest distance, and checking the distance on my GPS I discovered that my Dodge ODO is off by 2%-3%.

The difference between the size of the "standard" 265/R70 17 and the 275/70 R20 is approx. 4%.

This difference equates to approx. 0.5 mpg difference in fuel economy.

Any thoughts?

 

Well i had the 20" wheel but i down graded to a 17" and put a 35" tire on mine. So fuel stayed about the same. So im sure if i wouldnt have put the b***er tire the smaller rim would have helped me a little.

 

Yep, my SLT 03 4x4 Hemi's original build sheet states she came with the 17's. But, when I got her as a used truck, she was sporting 20's.
I do know that my speedo says 60mph but the sat nav says anything from 62-63 mph ???
I know I have the stupid 3:55 gears and crap standard lsd (soon to be a DTT ha ha ha) and she's a dog with the 20's and 275x60xR20 tyres on.

 

You will love the Detroit Tru Trac! And with 4:56 gears you can't go wrong! If you go with that setup you will have it made!

 

i have 17' A.R. victor wheels and i had originally thought about going to 20's, but for me that was just too much wheel and not enough tire-2 cents

 

Personally, 20s are fine on a 4x2, if you don't mind giving up a mpg or two because of the extra weight.
But on a 4x4, unless you are a pavement queen, you want as much sidewall as possible. You want what I call the three "F's" - Flex, Footprint & Flotation, on just about any off road situation I can think of. These are only obtained with as much meat on the wheel as possible...