Bill,
Just saw your post.
Remember that my truck is a 2012 Chevy 2500, but I have 285/75-17 Nitto Dura Grapplers. 3970# each. VERY stiff sidewalls. VERY STIFF.
My local indy shop likes Chevys and made them fit. 2 turns on the front T-bars and no rubbing.
In GM talk mine is a NNBS pickup and I have 7.5" wide OEM wheels.
Hope this helps.....and when are you coming north?
On edit- I spent almost all of this winter in 2WD and no weight in the bed. No problems with the DuraGrappler (highway tread) tires. And we live on a very steep private road.
John