It really is a bummer because these trucks look better with the bigger tires but it really does affect performance and I damn sure didn’t spend as much as I did on this truck just for looks. The crazy part is going up 1” and up in width .8” increases the tire weight by 20+ % I really feel like that’s the biggest factor. Hell braking even felt different , kinda like I was pulling a trailer even though I wasn’t. I don’t understand how guys running even bigger tires without regearing are not seeing and feeling the cons of the bigger tires.
General info here... I went from a 30# wheel to a 21.4# wheel with the same tire and gained ~1.5 mpg. Swapped in an AL driveshaft and gained ~0.9 mpg from one week to the next with no other changes to the truck. When I dropped back down to stock height, I gained ~1.0 mpg back... so to sum it up, went from the low 19's up to the mid 22's and possibly 23's by the end of the week with the most current tune change. Last 4 tanks wee 22.6, 22.5, 22.4 and 22.7. Note that there was an e-fan swap (could not measure any difference) and a lot of tuning changes that occurred.
Back when I had a 285-75-17 tire (current is a 285-70-17 tire) I was able to get 21~22 mpg on the hiway fairly easily by keeping speeds ~65ish (Minnisota & Cali). With the current tire & before all the current changes, ~20.X was a great tank. Was never able to really get much more than mid 20.x's for mpg. With that said, I did the math and the next tire going on is 5# heavier than what's coming off (plus whatever wear dropped the weight to at the end). Not sure if I'm going to be able to get back what I lost when I went down a size on the hiway but am going to give it a shot. There is a 60 day return limit on the tires I'm getting into next (not the same as the current one) so I have time to see how they do.
The tire swap is coming up in the next 4~6 weeks... This is on a 3rd gen G56 4wd truck...