IMHO 16" will have more tire selection options
16" wheels hub centric are a great choice in steel or forged aluminum. I've always have trouble finding load rating data for case aluminum wheels. I have found that steel wheels that are riveted have a higher load capacity than welded wheels, Chevy/GM riveted wheels have a code stamped at the valve stem area of wheel. Stud centric wheels must be torqued off the ground while the hub centric can be on the ground.
There are some great wheelsmiths out there that can build custom wheels.
285/75/16 (e) generally have a load rating of 3,750 lbs @ 80 psi so can be aired down safely on a heavy suburban. Some (d) load rated tires have a nice load rating at lower psi and work well w/suburban too. The 255/85/16 (e) option is great choice however finding them can be a challenge most of the time so having more than a few spares for any remote area would be best bet I carry 2 spares w/burb and add another for the trailer "my burb and trailer have same lug pattern", the 285/75/16 (e) is quite common.
1999 GMC K2500 BURBAN, NAVISTAR enhanced 6.5 td aftercooled, dual alt's, PSC p/s pump w/HD cooler, redundant FSD's, HEATH program, turbine/downpipe wrapped, 4" SS exhaust, real time OBD2 data logging w/device controller, EVANS waterless coolant @ zero (0) psi & 135 gpm pump, 4L80e w/kevlar and premium steel w/cryo treated input/output shafts running @ 100 deg. F & 140 deg F towing, all synthetic fluids, AMSOIL bypass system, MileMarker hydro, dual fuel tanks, and on and on, questions PM me.