Larger wheels vs gas mileage; And few other thoughts
 

Now I'm all wondering about what I really want in a truck. I want the denali front end but on the SLE or SLT. I like the SLT better cause it has the woodgrain and stuff. I contacted a salesman at a dealer to see if i can get the truck built specifically like i want it, with the denali front end on either of those other 2 models. I also lately have been falling in love with the larger wheels.

The 22 inch wheels just look so much more full. I wonder if gas mileage will decrease with the 22's vs the 20's, and the 20's vs the 18's? The larger the wheel the less gas mileage? If its a GM designed wheel it shouldnt matter if the wheels are larger as far as gas mileage? What about the speedometer being thrown off? I guess if it is ordered, they should have it all matched up at the factory?

I'm assuming when you say 18, 20 and 22 you are talking rim size. The diameter of the tire will affect gas milage not the rim size. I went from a 32 to a 33 inch tire and didn't notice a difference in gas milage. I'm sure there was but I didn't notice it. A large change like from a 32 to a 35 will cause you to down shift more often thus run at a higher RPM. Then you would notice the gas milage go down.

yeah i was talking bout rim size. So if i go from a 275 55 20 to a 285 45 22 then since that tire size is wider I will see some gas mileage change but it might be minimal?

I might not be accurate on the size of the 20's tire that gmc puts on them. I'm sure its a 275 something but cant remember if it was a 50 or 55, or maybe a 60