Longer answer:
3 leaf front, 6 leaf rear (if that changes ride height over the 2/5 "stock" spring setup, not sure) 33x10.5R15 on stock 15x8 ralleys clears with no rubbing.
Tire pics aways down
As you can see from the fronts there, lots of room up front (in front wheelwell), and enough in back (still front wheelwell) it APPEARS, even if the center of the hub was pushed up as high as the lower lip of the fender, (which would never happen due to bumpstops, swaybar, etc.) to clear no matter what.
On flat ground I jacked one front corner up until the other tire came off the ground, moved the wheels from stop to stop, and it could not rub...stock suspension just won't allow the axle to flex enough IMO, plus the tire width (which is important and why 12.5's rub) and wheel backspacing don't cause any more problems.
I'm by no means a hardcore wheeler (I like my fairly straight sheetmetal) but I believe I am qualified to say that no matter how hard I wheel this truck as is, those tires simply can't rub. I've had it offroad enough to believe if there was a problem, I would have found it.
And yes, there are so many variables that it is never a given that a tire that fits on one truck won't fit on another. I bought my tires from discount tire, and they (along with another place I didn't end up going to) *said* they would mount the tires for me, and take the tires back if they wouldn't clear, since I had no tires to bring the truck up to them with.