FORD 2015 F-550 v.2 - Manual (Page 271)

mph ( km/h) Letter
rating
168 (270) W
186 (299) Y
Note: For tires with a maximum
speed capability over 149 mph
(240 km/h), tire manufacturers
sometimes use the letters ZR. For
those with a maximum speed
capability over 186 mph (299
km/h), tire manufacturers always
use the letters ZR.
H. U.S. DOT Tire Identification
Number: 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
built. For example, the numbers
317 mean the 31st week of 1997.
After 2000 the numbers go to four
digits. For example, 2501 means
the 25th week of 2001. The
numbers in between are
identification codes used for
traceability. This information is
used to contact customers if a tire
defect requires a recall.
I. M+S or M/S: Mud and Snow, or
AT: All Terrain, or
AS: All Season.
J. Tire Ply Composition and
Material Used: Indicates the
number of plies or the number of
layers of rubber-coated fabric in
the tire tread and sidewall. Tire
manufacturers also must indicate
the ply materials in the tire and the
sidewall, which include steel,
nylon, polyester, and others.
K. Maximum Load: Indicates the
maximum load in kilograms and
pounds that can be carried by the
tire. (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.
L. Treadwear, Traction and
Temperature Grades:
*Treadwear The treadwear grade
is a comparative rating based on
the wear rate of the tire when
tested under controlled conditions
on a specified government test
course. For example, a tire graded
150 would wear 1½ times as well
on the government course as a tire
graded 100.
*Traction: The traction grades,
from highest to lowest are AA, A,
B, and C. The grades represent the
tire's ability to stop on wet
pavement as measured under
controlled conditions on specified
government test surfaces of
asphalt and concrete. A tire
marked C may have poor traction
performance.
268
Super Duty (), enUSA
Wheels and Tires