Ford 2015 F-150 Owner's Manual page 344

it needs to be repaired or replaced.
For your safety, tires that are
damaged or show signs of
excessive wear should not be used
because they are more likely to
blow out or fail.
Improper or inadequate vehicle
maintenance can cause tires to
wear abnormally. Inspect all your
tires, including the spare,
frequently, and replace them if
one or more of the following
conditions exist:
Tire Wear
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When the tread is worn down to
one sixteenth of an inch (2
millimeters), tires must be
replaced to help prevent your
vehicle from skidding and
hydroplaning. Built-in treadwear
indicators, or wear bars, which
look like narrow strips of smooth
rubber across the tread will
appear on the tire when the tread
is worn down to one sixteenth of
an inch (2 millimeters).
F-150 (TFC) Canada/United States of America, enUSA, Fourth Printing
Wheels and Tires
When the tire tread wears down
to the same height as these wear
bars, the tire is worn out and must
be replaced.
Damage
Periodically inspect the tire treads
and sidewalls for damage (such
as bulges in the tread or sidewalls,
cracks in the tread groove and
separation in the tread or
sidewall). If damage is observed
or suspected have the tire
inspected by a tire professional.
Tires can be damaged during
off-road use, so inspection after
off-road use is also
recommended.
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