I understand that even if you get a different diameter wheel, you can end up with roughly the same tire diameter due to the thickness of the tire itself.

However, I just got a message from somebody who said that he got 19 inch wheels (along with an Accessport and a BOV) and odo now registers 80 more miles per tank. WTF? Maybe he has the AP on economy mode?

Somebody enlighten me as to what a larger tire diameter will do to your speed/distance equipment vs. smaller. And, is there an actual fuel efficiency effect on the veh with different diameters, or is it just that the calibration on his equipment is off now that the wheels are bigger?

 

The weight of the wheel and tire will have an effect but the size should have a very small effect on MPG (But not 80 miles per tank). Unless it's way bigger or smaller and then it would probably be a negative effect.

Check these out:

Thread on same topic:
https://www.i-club.com/forums/showth...ht=speedometer

Tire Size Calc
http://www.discounttiredirect.com/di...foTireMath.jsp