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Maintenance
46
7
7. Uniform tire quality grading
Quality grades can be found where
applicable on the tire sidewall
between tread shoulder and maxi-
mum section width.
For example:
TREADWEAR 440
TRACTION A
TEMPERATURE A
Tread wear
The tread wear grade is a compara-
tive rating based on the wear rate of
the tire when tested under controlled
conditions on a specified govern-
ment test course. For example, a tire
graded 150 would wear one-and-a-
half times (1½) as well on the gov-
ernment course as a tire graded 100.
The relative performance of tires
depends upon the actual conditions
of their use, however, and may
depart significantly from the norm
due to variations in driving habits,
service practices and differences in
road characteristics and climate. Tires degrade over time, even when
they are not being used. Regardless
of the remaining tread, we recom-
mend that tires be replaced after
approximately six (6) years of nor-
mal service. Heat caused by hot cli-
mates or frequent high loading con-
ditions can accelerate the aging
process.
These grades are molded on the
side-walls of passenger vehicle tires.
The tires available as standard or
optional equipment on your vehicles
may vary with respect to grade.
Traction - AA, A, B & C
The traction grades, from highest to
lowest, are AA, A, B and C. Those
grades represent the tires ability to
stop on wet pavement as measured
under controlled conditions on spec-
ified government test surfaces of
asphalt and concrete. A tire marked
C may have poor traction perform-
ance.
The traction grade assigned to this
tire is based on straight-ahead brak-
ing traction tests, and does not
include acceleration, cornering,
hydroplaning, or peak traction char-
acteristics.
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747
Maintenance
Temperature -A, B & C
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 condi-
tions on a specified indoor laboratory
test wheel.
Sustained high temperature can
cause the material of the tire to
degenerate and reduce tire life, and
excessive temperature can lead to
sudden tire failure. The grade C cor-
responds to a level of performance
which all passenger car tires must
meet under the Federal Motor
Vehicle Safety Standard No. 109.
Grades B and A represent higher
levels of performance on the labora-
tory test wheel than the minimum
required by law.Tire terminology and defini-
tions
Air Pressure:The amount of air
inside the tire pressing outward on
the tire. Air pressure is expressed in
kilopascal (kPa) or pounds per
square inch (psi).
Accessory Weight: This means the
combined weight of optional acces-
sories. Some examples of optional
accessories are, automatic
transaxle, power seats, and air con-
ditioning.
Aspect Ratio: The relationship of a
tire's height to its width.
Belt: A rubber coated layer of cords
that is located between the plies and
the tread. Cords may be made from
steel or other reinforcing materials.
Bead: The tire bead contains steel
wires wrapped by steel cords that
hold the tire onto the rim.
Bias Ply Tire: A pneumatic tire in
which the plies are laid at alternate
angles less than 90 degrees to the
centerline of the tread. Cold Tire Pressure:
The amount of
air pressure in a tire, measured in
kilopascal (kPa) or pounds per
square inch (psi) before a tire has
built up heat from driving.
Curb Weight: This means the weight
of a motor vehicle with standard and
optional equipment including the
maximum capacity of fuel, oil and
coolant, but without passengers and
cargo.
DOT Markings: The DOT code
includes the Tire Identification
Number (TIN), an alphanumeric des-
ignator which can also identify the
tire manufacturer, production plant,
brand and date of production.
GVWR: Gross Vehicle Weight Rating
GAWR FRT: Gross Axle Weight
Rating for the Front Axle.
GAWR RR: Gross Axle Weight
Rating for the Rear axle.
Page 369 of 394

Specifications, Consumer information, Reporting safety defects
68
Recommended SAE viscosity
number Engine oil viscosity (thickness) has an
effect on fuel economy and cold weather
operating (engine start and engine oil
flowability). Lower viscosity engine oils
can provide better fuel economy and cold
weather performance, however, higher
viscosity engine oils are required for sat-
isfactory lubrication in hot weather. Using
oils of any viscosity other than those rec-
ommended could result in engine dam-
age.When choosing an oil, consider the
range of temperature your vehicle will be
operated in before the next oil change.
Proceed to select the recommended oil
viscosity from the chart.
CAUTION
Always be sure to clean the area
around any filler plug, drain plug, ordipstick before checking or drain-ing any lubricant. This is especiallyimportant in dusty or sandy areasand when the vehicle is used on unpaved roads. Cleaning the plugand dipstick areas will prevent dirtand grit from entering the engineand other mechanisms that couldbe damaged.
Temperature Range for SAE Viscosity Numbers
Temperature
Engine Oil *
1
°C
(°F)-30 -20 -10 0 10 20 30 40 50 -10 0 20 40 60 80 100 120
1. For better fuel economy, it is recommended to use theengine oil of a viscosity grade SAE 5W-20 (API Service SM
/ ILSAC GF-4). However, if the engine oil is not available,
select the proper engine oil using the engine oil viscosity
chart.
10W-30
5W-20, 5W-30