@ptrnfan
I wonder if the other tires on these trucks are also Load E (that's what I have on my Rebel), and that's what I needed on the Ecodiesel too.
One of the main reasons for buying this package was the Tires and Rims - I know that sounds kind of stupid, but here's my logic behind the 18" (33" tire). But the different tire pressures is kind of odd to me too - I really don't understand it ( I actually plan on adding air to the back when pulling camper & boat).
I use my truck a lot (seriously a lot) off-road - not rock crawling, not for playing in the dirt/mud, etc. - I hunt Moose, Deer, Partridge in the fall, and do a whole lot of camping and fishing. When I had my GMC it came with 20 inch rims and tires (32's I think it added up to), and to me, this just defeated the practicality of a truck.
Don't get me wrong the 20's were very very good on pavement, but the minute you took it off-road it just sucked - period. I was always afraid that I would bust a tire or screw up a rim... So that's why I went back to a larger tire as it fits my needs perfectly. I thought Load E was a very high rating in terms of loading capabilities, I guess I'll have to research on the differences a bit more.