Quote:
Originally Posted by Big Dave
Larger diameter wheels/tires are counter-productive and by no means a substitute for changing gearing. Larger diameter wheels add heights and frontal area and worse yet, add rotational inertia. If bigger wheels improved MPG, then all the "Bigfoot-Wannabe" lifted trucks should get terrific MPG.
|
I agree that increased rotational inertia and "in general" larger diameter tires will be counter-productive (for fuel economy), but I wonder if the effect is reduced on a vehicle with a taller ride height.
For example, a 4wd pick up truck has a tall ride height. So I speculate that on a truck with aero mods, increasing the tire diameter slightly (and possibly reducing the tread width), may bring the BSFC back into an efficient island; without significantly increasing the aero due to ride height increase, as there is already so much air traveling under the vehicle in its stock configuration.
Getting down to this level of detail, the amount of rolling resistance a particular set of tires produced would also have an impact. So, some educated tire shopping would be required.