i run my 31's at 29. that seem to be good for tire wear for that specific tire.
1977 Cherokee ChiefEdelbrock 1406, 33X12.50, front 1.5 inch shackle lift. AMC 360, th400 Quadra-Trac
2002 wrangler, stock 4.0, auto, 33X12.50 maxis buckshot, AEV Highline Body kit, Ford 9 inch rear end.
Soon to come mods: 4" full traction lift, 4.56 gears, 35X10.50R15 boggers, 35X12.50 cooper st tires, spooled rear end, and much more.