seems like if you got the same weight tires/wheels, but a couple inches bigger, then your MPG would go up.

is this true?

15" -> 2pi15 = 94.2
17" -> 2pi17 = 106.76

so you get 12.56 more inches out of every revolution of the wheel.

so 17's are 13.3% more efficient travel wise.

however, turning the wheel will require more rotational force, since the weight of the tire has spread outwards 2 inches.

 

ya but you dont save money the tires are alot more expensive