the f350 cab n chassis 4wd trucks,and or likely even the cab n chassis 2wd trucks came with more offset in rims to handle the wider tires.
like the f350 cab n chassis,the f-super duty (pre f-450) came with 235/75/16's.
however the truck posted in the first thread is an f350 pickup truck.these only came as 2wd's and they came with rims meant to run dual 215's.
if you put 235's on there and push the limits of the truck loading up like i do,there's no doubt in my mind i'd have constant blow outs.
when dual tires touch inside while rolling,this creates heat.
the other issues with going to a 235's even if you add an hub centric spacer,is that now with the increased rolling resistance of the wider tires fuel economy goes down even further,as does traction.duallies already suffer from this,and the wider meats would just make it worse.
i would stick with the 215's or if you wanted to go shorter tires,you can run 225's issue free.
you can do whatever you want,just the next time to put a load on,look down between the tires.forget way down on the tread.look up a bit where the sidewalls bulge from the weight.as long as you don't put enough weight on the truck to make the tire sidewalls bulge and touch each other,plus a little to account for bumps,then you won't need different rims or spacers.if you see the sidewalls touch,remove the weight and order what you need to resolve the issue,or you'll be out new tires and possibly that expensive dually bed.-torn off fenders.
