I was just reading an old blurb about Pirelli introducing a 65% Aspect ratio tire and claiming F.E. benefits due to reduced sidewall flexion etc, over a 85% tire. Now they said something about 65% being "ideal" but I dunno if at the time it was thought possible to go much lower.
So I've been wondering if the modern low profile tires such as 40% aspect ratio are even better in this regard or not.
I realise there's a bit of a problem in comparison, since when you go up a couple of wheel sizes you're usually getting fatter tires too, so likely to go from say a 175/65 to a 225/45. But I was thinking that if one was careful and found the right wheel and tire combo, i.e, as skinny as possible, while being as large as possible, whether the reduced rolling resistance would pay off over the width penalty.
So, anybody ever upsize the wheels and get an MPG benefit without changing overall wheel diameter significantly? Or find higher mpg after your 5% (or whatever) mileage loss or gain was calculated in?