We all know that taller tires give you a taller gear, but make you less aero. And shorter tires lower the vehicle making it more aero, and take less energy to get them up to speed (weight etc being equal). Would it then make the most sense to use shorter tires on a vehicle used mostly in city driving and taller tires for a vehicle that is used mostly on the highway?
It's odd what you ponder when you can't sleep, isn't it?