Refering to the TM 9-2320-272-10 for M934s, Table 1-10 gives front 90psi / rear 70psi for highways, and front 60psi /rear 30psi for cross country with 11x20 tires. Those pressures are assuming a full load, so you could probably reduce them for a smoother ride empty. I've seen a full range of pressures painted on the wheel wells, so I guess it was up to the unit to set tire pressures.