This thread provoked a lot of thought and led to a very significant discovery and lesson for me.
After reading this thread last night, I got thinking about the tires on the Expedition. They are not original, and the same tires (Goodyear Armour) were on an Excursion we were looking at before we bought the Expedition.
So, today, I made it a point to check: yep, LT265/70/17 Load range C. Uh oh!
I had been inflating them per the door jam, and after checking the spec's via Goodyear's site, they have been under-inflated by 15psi this entire time!!
To get the same load handling out of these tires as the original P-series tires, the rears have to be at 50psi! They were at 35. The front's need to be 45psi. They were 30.
I cannot get over how much this has improved the road feel.
This should be a sticky, as I imagine this occurence is far too common.