Never kept notes but it seems to be 2-5 psi. Oddly enough, when I was checking the pressure for a trip this week, both fronts were at 52 and the rears were at 72. The van did not throw any ESP codes thus I think the ESP is more concerned with sensing the diameter (wheel speed) at each corner using the ABS wheel speed sensors. SO if one corner or opposing corners is off, then a code is thrown. In more automated German vehicles the ABS system controls stability (wheel speed) in corners by varying brake pressure at the wheel.
The only idea that comes to mind why I had such a large pressure differential front to rear is that I had the front tires spin balanced last week and the shop may have had to lower the front pressures for more grip on their machine, then forgot to air up after.
2014 Little Guy 5x10 Silver Shadow