FORD 2011 F-550 v.1 - Manual (Page 310)

Do not rock the vehicle if the engine is not at normal operating
temperature. Do not rock the vehicle for more than a minute. The
transmission and tires may be damaged or the engine may
overheat.
Refer to Gauges in the Instrument Cluster chapter for transmission
fluid temperature information.
WARNING: Do not spin the wheels at over 35 mph (55 km/h).
The tires may fail and injure a passenger or bystander.
Driving
310
2011 F-250/350/450/550 (f23)
Owners Guide, 1st Printing
USA (fus)