Ford Thunderbird (2004 year). Manual — part 47

7. H: Indicates the tire’s speed rating. The speed rating denotes the
speed at which a tire is designed to be driven for extended periods of
time under a standard condition of load and inflation pressure. The tires
on your vehicle may operate at different conditions for load and inflation
pressure. These speed ratings may need to be adjusted for the difference
in conditions. The ratings range from 159 km/h (99 mph) to 299 km/h
(186 mph). These ratings are listed in the following chart.

Note: You may not find this information on all tires because it is not
required by federal law.

Letter rating

Speed rating - km/h (mph)

Q

159 km/h (99 mph)

R

171 km/h (106 mph)

S

180 km/h (112 mph)

T

190 km/h (118 mph)

U

200 km/h (124 mph)

H

210 km/h (130 mph)

V

240 km/h (149 mph)

W

270 km/h (168 mph)

Y

299 km/h (186 mph)

Note: For tires with a maximum speed capability over 240 km/h (149
mph), tire manufacturers sometimes use the letters ZR. For those with
a maximum speed capability over 299 km/h (186 mph), tire
manufacturers always use the letters ZR.

8. M+S or M/S: Mud and Snow. or
AT: All Terrain. or
AS: All Season.

9. U.S. DOT Tire Identification Number (TIN): 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 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 marketing codes used at the manufacturer’s
discretion. This information is used to contact customers if a tire defect
requires a recall.

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192

10. Tire Ply Composition and Material Used: Indicates the number of
plies indicates 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.

11. Maximum Load: Indicates the maximum load in kilograms and
pounds that can be carried by the tire. Refer to the tire label or the
safety certification label, located on the B-Pillar or the driver’s door, for
the correct tire pressure for your vehicle

12. 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 one and one-half (1

1

⁄

2

) 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.

• Temperature: The temperature grades are A (the highest), B and C,

representing the tire’s resistance to the generation of heat and its
ability to dissipate heat when tested under controlled conditions on a
specified indoor laboratory test wheel.

13. Maximum Permissible Inflation Pressure: Tire manufactures
maximum permissible pressure and/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 either the tire label or certification label which is
located on the structure by the trailing edge of the driver’s door or the
edge of the driver’s door. The cold inflation pressure should never be set
lower than the recommended pressure on the label.

Note: You may not find this information on all tires because it is not
required by federal law.

The tire suppliers may have additional markings, notes or warnings such
as standard load, radial tubeless, etc.

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193

Additional information contained on the tire sidewall for “LT” type
tires

“LT” type tires have some additional
information than those of “P” type
tires; these differences are
described below:

1. LT: Indicates a tire, designated by
the Tire and Rim Association
(T&RA), that is intended for service
on light trucks.

2. Load Range/Load Inflation
Limits: Indicates the tires
load-carrying capabilities and its
inflation limits.

3. Maximum Load Dual kg (lbs.)
at kPa (psi) cold: Indicates the
maximum load and tire pressure
when the tire is used as a dual; a
dual is defined as when four tires are put on the rear axle (a total of six
or more tires on the vehicle).

4. Maximum Load Single kg (lbs.) at kPa (psi) cold: Indicates the
maximum load and tire pressure when the tire is used as a single; a
single is defined as when two tires (total) are put on the rear axle.

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194

Information on “T” type tires

T145/80D16 is an example of a tire
size.

Note: The temporary tire size for
your vehicle may be different than
this example.

1. T: Indicates a type of tire,
designated by the Tire and Rim
Association (T&RA), that is
intended for temporary service on
cars, SUVs, minivans and light
trucks.

2. 145: Indicates the nominal width
of the tire in millimeters from
sidewall edge to sidewall edge. In
general, the larger the number, the
wider the tire.

3. 80: Indicates the aspect ratio
which gives the tires ratio of height to width. Numbers of 70 or lower
indicate a short sidewall.

4. D: Indicates a “diagonal” type tire.
R: Indicates a “radial” type tire.

5. 16: Indicates the wheel or rim diameter in inches. If you change your
wheel size, you will have to purchase new tires to match the new wheel
diameter.

Location of the tire label

You will find a tire label containing tire inflation pressure by tire size and
other important information located on the B-Pillar or the driver’s door.

TIRE CARE

Improper or inadequate vehicle maintenance can also cause tires to wear
abnormally. Here are some of the important maintenance items

Tire inflation pressure

Use a tire gauge to check the tire inflation pressure, including the spare,
at least monthly and before long trips. You are strongly urged to buy a
reliable tire pressure gauge, as automatic service station gauges may be
inaccurate.

SPA

RE TIRE

TE

M

PO

RA

RY

US

EO

NL

Y

IN

FLA

TE

TO

60

P .S

.I

.T

T14

5/80D16 105M

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195