My trucks get a whopping 17mpg, could actually be better but the bigger tires make the speedo a little slow so the mileage might be a little better. The sad part is this truck is a regular cab short bed v6 5spd 2wd. My last Silverado a fully loaded extended cab, 4wd, auto, with the h.o. 5.3 and I got 18-22mpg. I can't wait to swap in a 6.0l and the 6spd tranny.
but yea, the 18s fucked it up for a while... we have the 17's back on it.
