MPG change when upgrading to 20"?

[ard]

1. JCL didnt say "mass" he said 'inertia'.... the different wheel/tire will have a different rotational inertia.

2. My "3-4 mpg" was a total joke.

3. IMO the difference in 'rolling resistance' is MUCH smaller than all the other components that influence mileage (like 12 square feet of frontal area driving through the air!!) Tirerack did an analysis that showed a whopping 20% increase in rolling resistance would only have a theoretic impact of 3% on mpg. Three percent. While they are in the business of selling wider tires, I thought it was a pretty rational explanation.

[jinhao]

good to know. btw contact area of any tire remains the same if inflated to the same PSI and same vehicle.

going from dueller h/p rft to conti dws or nitto motivo 275/40R20