My 2013 XLE came with the standard 235/60R17 tire size which when doing a highway mileage marker test indicated 1 mile on the odometer at the .9 mile road marker. As far as I know Toyota MPG stats are based on the odometer reading which obviously is incorrect. Speedometer was also off.I recently started using Fuelly again, after a several year break. I was curious how the indicated MPG on the Sienna display compared to actual MPG from calculating on fuel-ups, so when recording in Fuelly, I added notes for the indicated MPG, and started resetting the indicated MPG at each fuel up. I'm only 4 fuel ups in, but this is what it looks like so far:
Currently, I've been doing a lot more highway driving than I have been, with some 45 mile commutes that are mostly highway and/or freeway. 60 MPH if I take the highway route, 75 MPH if I take the freeway route.
2014 Sienna LE with 122,500 miles, with new spark plugs a couple thousand miles ago. Running new Michelin CrossClimate2 tires.
A couple of years ago I replced the OEM tires with 235/65R17's, a taller tire, which is spot on with the highway mileage markers. Unfortunately, as you probably guessed, my MPG dropped about 10%.
To answer the question which I'm sure I'll get on whether the taller tires rub or not, the answer is that when the steering wheel is totally turned to the left or the right (locked out) there is a very slight rub that can be heard.