Except for the stock Rebel wheel, they are 8".
I had 285/70/17's on stock 7" wheel - Michelin Defender LT's E-load.
You could push on the bumper and watch the rim and tire move in and out with the tread stationary - which is exactly what happened when driving and you could feel it under the right conditions.
Hitting a bump in the road on a bend and you could feel the truck jump out to the side - tread itself felt planted - just a freaky unsafe feeling. Tire pressure ranged from 45-70 psi and it still did it.
With that size tire the rec. rim width is 7.5"-9", that is the spec the tire manufacturers rec.
Currently have 275/60/20 General HTS 60 X-loads on Laramie Longhorn 9" wheels - truck now handles much more like a car and haven't looked back.
Just giving my experience. I tend to use the truck fairly loaded and at highway speeds almost exclusively.