Are you looking for height or width, or both?
IMO, and this is just an opinion because people mount them all the time, I think 285/70's are too wide for the OEM rims. I never felt they looked exactly right either. I think 255/80's are a better fit. Gives you some extra height without ballooning the tires out. Not to mention the wider the tire the more wear is put on the front end as well as throws more crap along the side of the truck.
265/70/17 = 10.4" tread width, 7.3" sidewall, 31.6" overall height
285/70/17 = 11.2" tread width, 7.9" sidewall, 32.7" overall height
255/80/17 = 10.1" tread width, 8" sidewall, 33" overall height.
255/80's would make the truck set roughly 3/4" higher while maintaining roughly the same width, 285/70 would raise the truck roughly 1/2" while adding close to an inch on the tread width.
These are rough measurements and will vary slightly by tire manufacturer and is assuming proper rim width but is a good general comparison.
Isnt new tire shopping so much fun? For the first time in my Dodge/Ram ownership I will be retaining the OEM size . They finally got that part right with the 18" wheels/tire size.