someotherguy
+1y
Well at minimum you need some XL or LT type tires on there. The two sizes you listed are closer to 2.5" in difference, not 3", and also remember it's only going to bring you half that higher off the ground.
Not a dually application but on my '94 C2500LD extended cab I ran Toyo Proxes S/T which are meant for trucks; instead of some wimpy 1300-1500 lb rating, the size I ran was like 2000 lbs I think.
On my new project, the '58 Apache on the '94 C3500 dually chassis, it had passenger car (standard load) 16's on the front trying to hold up the weight of the 6.5TD and NV4500. No good! I put BF Goodrich Commercial T/A in an E load range, 215/85/16 (stock Ford size, easy to find) they have a max load of 2680 lbs at 80 psi, though I've only got them around 60 for my needs.
Richard