[Big Dave]

This squares with pickup truck experience. Bigger diameter = lower mileage.

Why do the best MPG cars use little tires? Think their engineers know a thing or two?

Rotational moment of inertia goes up with the square of radius. This increases the rotational moment of those four "flywheels" at the corners. Everytime you accelerate, you have to pour energy into those flywheels to speed them up. In a perfect world a generator recoups that energy. That is part and parcel of a hybrid's MPG superiority.