I added 1.25 from HRG and the 245s and noticed nothing statistically significant. Mind you, with my work still bring from home. Much was the crap MPG to start with. Little 1-4mi trips. But on freeway averages were still 22-23.
with all my daily kit I’m average about 19.3. But it’s been windy and hothot hot since then. Neither of those good on mpg. So…. Waiting for cooler times to reevaluate.
I'm averaging 20-ish mpg lots of short city trips and limited highway with K02s in 245 65 17. But I am not thinking about it that way. Switching from street tires (that won't work offroad) to offroad tires is like putting the tires on the car that should have come on it in the first place for my needs. The reverse equivalent would be lowering the car and removing the roof rails and asking what mpg you gained.
Everything I’ve done to my BL I consider it a fair trade off. But with phoenix summers it’s hard to judge true MPG. No turbo does great in 110+. BUT I have been presently surprised at the lack of power drop. My 2015 stang was a dog in summer heat. Rest of the year she hopped like a rabbit running from a hound.
Bronco? She moves the same… she just more thirsty.