Just looked this size up on some sample google images... oh yes.... this would be ideal

 

I think you could fit those without much issue on the stock 20" wheels. Perhaps a little trimming here and there.

 

Funny, I just pulled the 295/55R 20 BF Goodrich Baja off my 2019 Lariat yesterday because of the highway noise and mpg.

went with Cooper 275/55R20 and sold off the Baja for $200. Much quieter and the aggressive look is still there though somewhat diminished.

I'm not going offroad and at my age peace and quiet are more important than a macho appearance. My macho appearance left me a few decades ago! 😄

FWIW, the 295/55 fit well with no rubbing.

 

If you mean the KO2, then that is a load range E in that size and weighs a healthy 64 lbs. You added close to 20 lbs per tire and your tire/wheel combo was probably north of 100lbs. Im sure that did hurt your mileage.

If you are more selective about what tires you use you can avoid the MPG and noise issues. I am running 315/70R17 Goodyear Territory MT's that are only 53 lbs each, and on a 17" wheel, were lighter than my stock 275/55R20's on the stock 20" wheels. MPG's barely changed. Before that I was running 315/70R17 Load Range C KO2's that was 63 lbs, but my 17" wheels were much lighter than 20" wheels and so my setup was probably 20 lbs lighter than yours even with the heavier tires.