Sweet ride. Did you compare actual speed diff with GPS, or just factor in the theoretical size difference from 245/70R17 in your calculations?
I went with the measured sizes and calculated the difference in distance traveled represented as a percentage. I have run 255/75 before on a 4th gen, so I was pretty familiar with what I was getting. When I considered my biggest gripe with the 5th gen I previously owned (mileage) I recalled that the 255/75 size has a slight advantage being only 10in wide, but still worthwhile upgrade over the 30.5" diameter tires that came stock. Obviously these rigs will run 33" tires stock, so it required some self control, lol. I've got about 600 miles on the tires now and I'm very satisfied!
Reason why I ask is cause the 6th gen speedometer seems to be off (fast) even for people with a 265/70R18 stock size. So I wonder if SR5s are just even more egregiously inaccurate from the factory and putting 255/75R17 on pretty much dials it in properly, thus possibly making your MPG calculations close to accurate without adjustments
This is similar to what I am seeing with Wyoming highways speeds in to 80-85mph range. I’m also constantly battling wind as well. Put 250 miles on yesterday and fought head winds both directions. I have yet to break 20mpg.
running 255/75/17 KO2's on my 2021 and the speedo is about spot on with the larger tires now. Unfortunately between accurate miles and heavier tires the mpg also dropped
dash/odo says 18mpg avg but fuelly which goes off of actual gas put in vs odo reading said 17.6. Is odometer off enough from the factory that GPS would be different? Tires I'm running are stock size for the ORP just with more tread (265/70/r18 toyo at3 load SL)
