FORD 2015 F-550 v.1 - Manual (Page 276)

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 and 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 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.
Note: 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.
273
Super Duty (), enUSA
Wheels and Tires