I, personally, haven't seen any reported issues. However, there are risks that i can see. First, you'd likely have to lift the truck a bit (3") or so to make sure the tires don't rub. Next, the new wheels and tires would be heavier, so they would put more of a strain on the rear differential and axles. You'd also likely see lower mpg's due to the higher rolling resistance and more weight not to mention your speedometer would be messed up if you didn't find a way to reprogram it. Bigger tires would provide more ground clearance and maybe some more grip (depending on tire choice) offroad, but it sounds like the downsides are something to consider...

 

The only convincing no-no I've heard is to *not* put different size (diameter) tires on front vs. back. The difference in size eats the differential, at least when it's engaged. (Which is at least every time you step on the gas from a stop)

- Chip