Mehoff... A lot of guys are going with a 30 or 35 series tire. I tried to apply a bit of logic as well aesthetics weighing heavily on my choice.
But... the logic was these few items:
1. weight of the truck (They aren't light!!!!) So a thin side wall doesnt offer much protection to potholes
2. The combination of wheel and tire is 97 lbs! This is all "unsprung weight" and yet again your tire is the only suspension your wheel itself has, so a bigger sidewall will help save your wheels.
3. Ride quality... again with the "cushioning" a taller side wall gives. (I drive my truck daily)
Beyond that I wanted a little "meatier" look for the sake of the look I wanted with he truck. But also it filled the fenders very well and looks good (in my opinion)
Most of the pictures you'll see will be a 30 series, so just bare that in mind.
Hope this helps.