2002 Tahoe LT with the 5.3L V8. 3.73 gears, 2 inch coil spacer lift with F150 torsion key crank. Nitto Terra Grappler 295 / 70 / R17 tires. Also have the BlackBear Performance tune that I love. They actually rode around in my truck with their computer connected to the OBD port and tuned the engine program to what I needed. Definitely a step above a "plug in" over the counter tune. I can get about 14-15 MPG highway on a long trip so long as I am gentle with the skinny pedal. Never tried to figure out the around-town MPG.
Lots more info in my build thread if you need anything.
2001 Suburban 2500 LT
8100 Vortec with Black Bear 89 tune
3.73 gears
285/70/17 Michelin LTXMS2
2" torsion bar lift
Gibson cat-back exaust
electric fans
Average 11 around town and upwards of 16 on the highway. The Black Bear tune really helps economy on the highway below 75mph. Set the cruise control and relax.
I just added the electric fans and am seeing an increase of maybe 1mpg. Roughly 40 miles more on a tank.
'02 k1500 Z71 Sub and the '05 k1500 Z71 Tahoe both wearing 265/70R17s, 'factory' size and pretty well matched. ~31" tall. Running a 285 will give you another 1/2" of ground clearance and cost you a 1/2" fenderwell clearance. You might be able to stuff 33s in there with a leveling kit or crank on the torsion bars. But might rub at full steering lock or full suspension compression. You'd need a lift to get anything bigger in there, I think.
33x12.5R17 tires. Stock keys cranked with the tabs flipped, 1.5 rear coil spring spacers, and a 1.5 inch body lift. End of the day, 4 inches of total lift in the front and 3 inches of total lift in the rear for $220. No rub when flexed with 9 inch wide and 4.5 inch backspaced wheels.
BF Goodrich AT/KO2 LT34/10.5R17 on OEM 17" rims, 3.73diff, 2" lift/3" keys, 1" wheel spacers for stability (usually has RTT on top) after trimming wheel studs to not hit rims. No fender trimming. Would like to go with lower gears but 4.56 too low / 4.11 not quite enough so still searching.
99 2500 Suburban. Currently 4.10 gears Goodyer MTR 37/12.50/16.5" tires 4 inch "lift". No real change in fuel mileage (diesel), driving is everything from highway to rock crawling. Future plans are 4.88 gears and 40" tires, with some fender trimming.
It came with LT245/75/16s, Ive run LT265/75/16 and LT285/75/16 with no lift, no torsion bar crank.