Got it. Makes more sense now. Just need to decide style over range now.The overall diameter is the same, it's the metal hub that is 16 or 17 inches. With a 17" wheel the wall of the tyre, the rubber part, is smaller so that the hub can be larger.
So that means that the tyre wall needs to be stiffer and it needs to be wider. That in turn means more friction and lower range/MPG, and a harsher ride with more noise. But it looks cool if you are into that.