FORD 2013 F-550 v.1 - Manual (Page 351)

Note: Do not reduce tire pressure to change the ride characteristics of
the vehicle. If you do not maintain the inflation pressure at the levels
specified by Ford, your vehicle may experience a condition known as
shimmy. Shimmy is a severe vibration and oscillation in the steering
wheel after the vehicle travels over a bump or dip in the road that does
not dampen out by itself. Shimmy may result from significant
under-inflation of the tires, improper tires (load range, size, or type), or
vehicle modifications such as lift-kits. In the event that your vehicle
experiences shimmy, you should slowly reduce speed by either lifting off
the accelerator pedal or lightly applying the brakes. The shimmy will
cease as the vehicle speed decreases.
Maximum Inflation Pressure is the tire manufacturer’s maximum
permissible pressure or the pressure at which the maximum load can be
carried by the tire. This pressure is normally higher than the
manufacturer’s recommended cold inflation pressure which can be found
on the Safety Compliance Certification Label (affixed to either the door
hinge pillar, door-latch post, or the door edge that meets the door-latch
post, next to the driver’s seating position), or Tire Label which is located
on the B-Pillar or the edge of the driver’s door. The cold inflation
pressure should never be set lower than the recommended pressure on
the Safety Compliance Certification Label or Tire Label.
When weather temperature changes occur, tire inflation pressures also
change. A 10°F (6°C) temperature drop can cause a corresponding drop
of 1 psi (7 kPa) in inflation pressure. Check your tire pressures
frequently and adjust them to the proper pressure which can be found
on the Safety Compliance Certification Label or Tire Label.
To check the pressure in your tire(s):
1. Make sure the tires are cool, meaning they are not hot from driving
even a mile.
If you are checking tire pressure when the tire is hot (for example,
driven more than 1 mile [1.6 kilometers]), never bleed or reduce air
pressure. The tires are hot from driving and it is normal for pressures to
increase above recommended cold pressures. A hot tire at or below
recommended cold inflation pressure could be significantly
under-inflated.
Note: If you have to drive a distance to get air for your tire(s), check
and record the tire pressure first and add the appropriate air pressure
when you get to the pump. It is normal for tires to heat up and the air
pressure inside to go up as you drive.
350 Wheels and Tires
2013 F-250/350/450/550 (f23)
Owners Guide gf, 1st Printing
USA (fus)