Re: will they fit?
Depends on the year and the wheel backspace measurement.
On an '06, you can go to 285/70-17 with the stock 6" backspace. If you go to 315's, it will rub at full lock, but if you go to a 4.5" backspace, they will clear.
Older trucks ('03 and earlier, I think) had a 4.5" backspace as stock. Not sure what will or will not fit them.