
Glossary of Tire Terminology
•Tire label:A label showing the OE (Original Equipment) tire sizes,
recommended inflation pressure and the maximum weight the vehicle
can carry.
•Tire Identification Number (TIN):A number on the sidewall of
each tire providing information about the tire brand and
manufacturing plant, tire size and date of manufacture. Also referred
to as DOT code.
•Inflation pressure:A measure of the amount of air in a tire.
•Standard load:A class of P-metric or Metric tires designed to carry a
maximum load at 35 psi [37 psi (2.5 bar) for Metric tires]. Increasing
the inflation pressure beyond this pressure will not increase the tire’s
load carrying capability.
•Extra load:A class of P-metric or Metric tires designed to carry a
heavier maximum load at 41 psi [43 psi (2.9 bar) for Metric tires].
Increasing the inflation pressure beyond this pressure will not increase
the tire’s load carrying capability.
•kPa:Kilopascal, a metric unit of air pressure.
•PSI:Pounds per square inch, a standard unit of air pressure.
•Cold inflation pressure:The tire pressure when the vehicle has
been stationary and out of direct sunlight for an hour or more and
prior to the vehicle being driven for 1 mile (1.6 km).
•Recommended inflation pressure:The cold inflation pressure found
on the Safety Compliance Certification Label. See the completed
vehicle’s owner’s guide for the location of the Safety Compliance
Certification Label.
•Bead area of the tire:Area of the tire next to the rim.
•Sidewall of the tire:Area between the bead area and the tread.
•Tread area of the tire:Area of the perimeter of the tire that
contacts the road when mounted on the vehicle.
•Rim:The metal support (wheel) for a tire or a tire and tube assembly
upon which the tire beads are seated.
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G.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 81 mph (130 km/h) to 186 mph
(299 km/h). 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 - mph (km/h)
M 81 mph (130 km/h)
N 87 mph (140 km/h)
Q 99 mph (159 km/h)
R 106 mph (171 km/h)
S 112 mph (180 km/h)
T 118 mph (190 km/h)
U 124 mph (200 km/h)
H 130 mph (210 km/h)
V 149 mph (240 km/h)
W 168 mph (270 km/h)
Y 186 mph (299 km/h)
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.
Note:Vehicle speed is limited to either 65 mph (105 km/h) or 75 mph
(120 km/h).
H.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 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.
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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. Refer to the Safety Compliance
Certification Label for the correct tire pressure for your vehicle. See the
completed vehicle’s owner’s guide for the location of the Safety
Compliance Certification Label.
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 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.
M.Maximum Permissible Inflation Pressure:Indicates the tire
manufacturers’ 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 Safety Compliance
Certification Label. See the completed vehicle’s owner’s guide for the
location of the Safety Compliance Certification Label. The cold inflation
pressure should never be set lower than the recommended pressure on
the vehicle label.
The tire suppliers may have additional markings, notes or warnings such
as standard load, radial tubeless, etc.
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Additional Information Contained on the Tire Sidewall for “LT ”
Type Tires
“LT” type tires have some additional
information beyond those of “P”
type tires; these differences are
described below.
Note:Tire Quality Grades do not
apply to this type of tire.
A.LT:Indicates a tire, designated
by the Tire and Rim Association
(T&RA), that is intended for service
on light trucks.
B.Load Range/Load Inflation
Limits:Indicates the tire’s
load-carrying capabilities and its
inflation limits.
C.Maximum Load Dual lb (kg) at psi (kPa) cold:Indicates the
maximum load and tire pressure when the tire is used as a dual; defined
as four tires on the rear axle (a total of six or more tires on the vehicle).
D.Maximum Load Single lb (kg) at psi (kPa) cold:Indicates the
maximum load and tire pressure when the tire is used as a single;
defined as two tires (total) on the rear axle.
A
BC
BD
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At least once a month and before long trips, inspect each tire and check
the tire pressure with a tire gauge (including spare, if equipped). Inflate
all tires to the inflation pressure recommended by Ford Motor Company.
WARNING:Under-inflation is the most common cause of tire
failures and may result in severe tire cracking, tread separation
or “blowout”, with unexpected loss of vehicle control and increased risk
of injury. Under-inflation increases sidewall flexing and rolling
resistance, resulting in heat buildup and internal damage to the tire. It
also may result in unnecessary tire stress, irregular wear, loss of vehicle
control and accidents. A tire can lose up to half of its air pressure and
not appear to be flat!
You are strongly urged to buy a reliable tire pressure gauge, as automatic
service station gauges may be inaccurate. Ford recommends the use of a
digital or dial type tire pressure gauge rather than a stick type tire
pressure gauge.
Use the recommended cold inflation pressure for optimum tire
performance and wear. Under-inflation or over-inflation may cause
uneven treadwear patterns.
Always inflate your tires to the Ford recommended inflation pressure
even if it is less than the maximum inflation pressure information found
on the tire. The Ford recommended tire inflation pressure is found on
the Safety Compliance Certification Label or Tire Label. See the
completed vehicle’s owner’s manual for the location of the Safety
Compliance Certification Label or Tire Label. Failure to follow the tire
pressure recommendations can cause uneven treadwear patterns and
adversely affect the way your vehicle handles.
Maximum Permissible Inflation Pressure is the tire manufacturer’s
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 the Safety Compliance Certification Label or Tire
Label. See the completed vehicle’s owner’s manual for the location of the
Safety Compliance Certification Label or Tire Label. The cold inflation
pressure should never be set lower than the recommended pressure on
the Safety Compliance Certification Label or Tire Label.
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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.
If you are checking tire pressure when the tire is hot, (i.e. driven more
than 1 mile [1.6 km]), 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.
Note:If you have to drive a distance to get air for your tire(s), check
and record the tire pressure first and add the appropriate air pressure
when you get to the pump. It is normal for tires to heat up and the air
pressure inside to go up as you drive.
2. Remove the cap from the valve on one tire, then firmly press the tire
gauge onto the valve and measure the pressure with the tire gauge.
3. Add enough air to reach the recommended air pressure
Note:If you overfill the tire, release air by pushing on the metal stem in
the center of the valve. Then recheck the pressure with your tire gauge.
4. Replace the valve cap.
5. Repeat this procedure for each tire, including the spare.
Note:Some spare tires operate at a higher inflation pressure than the
other tires. For T-type/mini-spare tires (seeDissimilar Spare
Tire/Wheel Informationsection for description): Store and maintain at
60 psi (4.15 bar). For full-size and dissimilar spare tires (seeDissimilar
Spare Tire/Wheel Informationsection for description): Store and
maintain at the higher of the front and rear inflation pressure as shown
on Safety Compliance Certification Label or the Tire Label.
6. Visually inspect the tires to make sure there are no nails or other
objects embedded that could poke a hole in the tire and cause an air
leak.
7. Check the sidewalls to make sure there are no gouges, cuts or bulges.
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Tire Inflation Information
WARNING:An inflated tire and rim can be very dangerous if
improperly used, serviced or maintained. To reduce the risk of
serious injury, never attempt to re-inflate a tire which has been run flat
or seriously under-inflated without first removing the tire from the
wheel assembly for inspection. Do not attempt to add air to tires or
replace tires or wheels without first taking precautions to protect
persons and property.
All tires with Steel Carcass Plies (if equipped):
This type of tire utilizes steel cords in the sidewalls. As such, they
cannot be treated like normal light truck tires. Tire service, including
adjusting tire pressure, must be performed by personnel trained,
supervised and equipped according to Federal Occupational Safety and
Health Administration (OSHA) regulations. For example, during any
procedure involving tire inflation, the technician or individual must
utilize a remote inflation device, and ensure that all persons are clear of
the trajectory area.
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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
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.
WARNING: Age
Tires degrade over time depending on many factors such as
weather, storage conditions, and conditions of use (load, speed,
inflation pressure, etc.) the tires experience throughout their lives.
In general, tires should be replaced after six years regardless of tread
wear. However, heat caused by hot climates or frequent high loading
conditions can accelerate the aging process and may require tires to be
replaced more frequently.
You should replace your spare tire when you replace the road tires or
after six years due to aging even if it has not been used.
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