Ford F-250 Owner's Manual page 233

Tires, Wheels and Loading
Understanding your tire pressure monitoring system (TPMS)
The tire pressure monitoring system measures pressure in your four road
tires and sends the tire pressure readings to your vehicle. The low tire
pressure warning light will turn on if the tire pressure is significantly low.
Once the light is illuminated, your tires are under-inflated and need to be
inflated to the manufacturer's recommended tire pressure. Even if the
light turns on and a short time later turns off, your tire pressure still
needs to be checked. Visit www.checkmytires.org for additional
information.
When your temporary spare tire is installed
When one of your road tires needs to be replaced with the temporary
spare, the TPMS will continue to identify an issue to remind you that the
damaged road wheel/tire needs to be repaired and put back on your
vehicle.
To restore the full functionality of the tire pressure monitoring system,
have the damaged road wheel/tire repaired and remounted on your
vehicle. For additional information, refer to Changing tires with a
TPMS in this section.
When you believe your system is not operating properly
The main function of the tire pressure monitoring system is to warn you
when your tires need air. It can also warn you in the event the system is
no longer capable of functioning as intended. Please refer to the
following chart for information concerning your tire pressure monitoring
system:
233
2011 F-250/350/450/550 (f23)
Owners Guide, 3rd Printing
USA (fus)