FORD 2002 F-550 v.2 - Manual (Page 271)

Tire inflation information
The F450 and F550 vehicles are equipped with a tire that is an all-steel
radial. All-steel radial tires utilize steel cords in the sidewalls, and also
require increased inflation pressures of up to 95 psi. As such, they
cannot be treated like normal light truck tires. Tire service, including
adjusting tire pressure, must be performed by personnel trained,
supervised and equipped according to Federal Occupational Safety and
Health Administration (OSHA) regulations. For example, during any
procedure involving tire inflation, the technician or individual must
utilize a remote inflation device, and insure that all persons are clear of
the trajectory area.
Maintenance and Specifications
271