FORD 2008 E-450 v.3 - Manual (Page 146)

vehicle, the weight of the equipment must be subtracted from the
payload listed on the Tire Label in order to determine the new payload.
WARNING: The appropriate loading capacity of your vehicle can
be limited either by volume capacity (how much space is
available) or by payload capacity (how much weight the vehicle should
carry). Once you have reached the maximum payload of your vehicle,
do not add more cargo, even if there is space available. Overloading or
improperly loading your vehicle can contribute to loss of vehicle
control and vehicle rollover.
Example only:
2008 Econoline (eco)
Owners Guide (post-2002-fmt)
USA (fus)
Tires, Wheels and Loading
146