Tire aspect ratio and fuel mileage question ?

[Green Machine]

If everything else was the same, tire width and over all height, which tire would roll easier, a 15 inch wheel with a 75 aspect ratio or say a 17 inch wheel with a 60 or 50 aspect ratio tire ???

Also, related but not the same, if geared so cruise rpm is the same, would a smaller diameter tire or a taller diameter tire roll easier ?

I know that wider rolls harder too, but is it measurable mpg difference ??