Ford 750 2009 Owner's Manual page 137

Under no circumstances should your vehicle be loaded in excess of the
GVWR or GAWR. It is the operator's responsibility to ensure that neither
the axle capacities, spring capacities, tire capacities nor the vehicle rated
GVWR is exceeded.
WARNING: Do not exceed the GVWR or the GAWR specified on
the Safety Compliance Certification Label.
WARNING: Do not use replacement tires with lower load
carrying capacities than the originals because they may lower
the vehicle's GVWR and GAWR limitations. Replacement tires with a
higher limit than the originals do not increase the GVWR and GAWR
limitations.
WARNING: Exceeding any vehicle weight rating limitation could
result in serious damage to the vehicle and/or personal injury.
Unloaded or lightly loaded vehicles
The braking system has been designed to safely stop your vehicle when
fully loaded to its GVWR.
2009 F-650/750 (f67)
Supplement
USA (fus)
Driving
137