Timely resurrection.
I just swapped the tires/wheels on my '11 Forester with another Forester('13) owner. OEM for me was 225/55/17 alloys and I swapped for his 215/65/16 alloys (+$150), my tires had about 16K miles on them, his had about 4K miles.
When we swapped we weighed each wheel/tire combo with the 17s weighing in at 45.8 lbs and the 16's weighing in at 42.2 lbs. Unfortunately, I could not do ABA testing
The diameter is about the same (not quite but within 1% with the 16's being slightly taller). I'm not expecting much if any FE improvement but I got $150 in my pocket already and 16" tire selection is much better and they are somewhat cheaper than 17's. Don't really care much about the looks.
When the current tires wear out I'll replace them with 215/70/16's for about a 4% increase over the OEM tire/wheel height. My Forester has a manual transmission with a 4.11 final drive ratio so that's when I'm expecting to see some FE improvement.
Comments?