Bek, did I miss it or did you not mention the model of tire? Im curious what they are.
as for pressures, its interesting to look at that chart done by the fellow who puts out that Bike Quarterly magazine, his chart is supposed to give you an optimized pressure for a given tire width and weight on it. Ive always found the numbers to be too low, as in my experience, when you are dealing with roads that can have sharp edged potholes, his recommendations just seem too low.
The other factor I find that comes into play is how a tire feels when going around a corner at a hefty lean angle and good speed--here my observations are all from "gut feeling" on interpreting how a bike moves around on its tires in a fast corner. Nothing scientific, and certainly only from my own experience of going fast around corners on two wheels, motorized and non motorized--but I do trust my instincts on this and am not comfortable if there is too much movement.
On the topic of cornering and road surfaces, a daily ride for me can range from perfect tarmac to really bad sharp edged potholes, and from straight flat roads to downhill turns at 40-50kph. I can also have nothing on the bike or a pannier with 10lbs of stuff in it easily, so the long and short of it is that I dont like to let my tires run too low just because of all the variables.
all that said, its really neat to hear of the pressures you guys are running on your fatties, will try to remember these numbers if and when I try some 50s.
Your 'gut feeling' is pretty good. Optimal tire pressure isn't fixed - it can vary with road conditions and riding speed even with the same rider and bike set-up. Not much different than a car really.