FORD 2007 F-550 v.1 - Manual (Page 140)

Tire wear
When the tread is worn down to
1/16th of an inch (2 mm), 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 1/16th of an inch (2 mm).
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.
Age
Tires degrade over time, even when they are not being used. It is
recommended that tires generally be replaced after 6 years of normal
service. Heat caused by hot climates or frequent high loading
conditions can accelerate the aging process. You should replace the
spare tire when you replace the other road tires due to the aging of
the spare tire.
U.S. DOT Tire Identification Number (TIN)
U.S. and Canada Federal regulations require tire manufacturers to place
standardized information on the sidewall of all tires. This information
identifies and describes the fundamental characteristics of the tire and
also provides a U.S. DOT Tire Identification Number for safety standard
certification and in case of a recall.
This begins with the letters “DOT” and indicates that the tire meets all
federal standards. The next two numbers or letters are the plant code
designating where it was manufactured, the next two are the tire size
code and the last four numbers represent the week and year the tire was
2007 F-250/350/450/550 (f23)
Owners Guide (post-2002-fmt)
USA (fus)
Tires, Wheels and Loading
140