To put things in perspective with another example, on my drop bar bike with 28mm slicks, bike weighs about 30lbs with water, me at 140 and let's say 10-15 lbs of one pannier of stuff that I commute with--I regularly run 90psi in the rear and 85 in the rear---AND I know it goes down at least 5psi to 10 psi before I get around to pumping up again.

I always used to think the max pressure was best, but reading about losing efficiency over bumps (force going into frame) getting less beast up as the rider, and it being easier on the rims and spokes, made me experiment and consequently reduce pressures.
At whatever the tire width.