that's very similar to what I'm seeing on my gladiator 37 BFGs and 5.13's. 18-ish with normal driving in Atlanta traffic/commute.
I went down to savannah about a month ago without any agenda, just wanted to see what I could get so I set it at 60-65 in the right lane and got almost 22 over the trip, so it's definitely possible to get better MPGs, just have to drive it like the brick shaped vehicle it is.
And when I need to tow my boat, having the 5.13's is night and day difference after having 4.10's for the first few trips.
Update on the tires, Noise levels and ride are good. Road noise is pretty good with a low hum at highway speeds but no loud anoying drowning. Ballace is good and not noticing any out of round or tire related issue of yet. Tire have only 800 miles on them due to the truck being in the shop for 2 weeks over gear issues. Currently running 30 PSI and seems to be close to the right PSI for my jeep weight it's currently at.