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(B) Tire Width:The three-digit number indicates
the tire section width in millimeters from sidewall
to sidewall.
(C) Aspect Ratio:A two-digit number that
indicates the tire height-to-width measurements.
For example, if the tire size aspect ratio is 60,
as shown in item C of the illustration, it would
mean that the tire’s sidewall is 60 percent as high
as it is wide.
(D) Construction Code:A letter code is used to
indicate the type of ply construction in the tire.
The letter R means radial ply construction;
the letter D means diagonal or bias ply
construction; and the letter B means belted-bias
ply construction.
(E) Rim Diameter:Diameter of the wheel in
inches.
(F) Service Description:These characters
represent the load range and speed rating of the
tire. The load index represents the load carry
capacity a tire is certi ed to carry. The load index
can range from 1 to 279. The speed rating is
the maximum speed a tire is certi ed to carry a
load. Speed ratings range from A to Z.Tire Terminology and De nitions
Air Pressure:The amount of air inside the tire
pressing outward on each square inch of the
tire. Air pressure is expressed in pounds
per square inch (psi) or kilopascal (kPa).
Accessory Weight:This means the combined
weight of optional accessories. Some examples of
optional accessories are, automatic transmission,
power steering, power brakes, power windows,
power seats, and air conditioning.
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.
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Different Size Tires and Wheels
If you add wheels or tires that are a different size
than your original equipment wheels and tires,
this may affect the way your vehicle performs,
including its braking, ride and handling
characteristics, stability, and resistance to rollover.
Additionally, if your vehicle has electronic
systems such as, anti-lock brakes, traction control,
and electronic stability control, the performance
of these systems can be affected.
{CAUTION:
If you add different sized wheels, your
vehicle may not provide an acceptable
level of performance and safety if tires not
recommended for those wheels are
selected. You may increase the chance
that you will crash and suffer serious
injury. Only use GM speci c wheel and
tire systems developed for your vehicle,
and have them properly installed by a GM
certi ed technician.SeeBuying New Tires on page 411and
Accessories and Modi cations on page 332for
additional information.
Uniform Tire Quality Grading
Quality grades can be found where applicable on
the tire sidewall between tread shoulder and
maximum section width. For example:
Treadwear 200 Traction AA Temperature A
The following information relates to the system
developed by the United States National Highway
Traffic Safety Administration (NHTSA), which
grades tires by treadwear, traction, and
temperature performance. This applies only to
vehicles sold in the United States. The grades are
molded on the sidewalls of most passenger car
tires. The Uniform Tire Quality Grading (UTQG)
system does not apply to deep tread, winter-type
snow tires, space-saver, or temporary use
spare tires, tires with nominal rim diameters of
10 to 12 inches (25 to 30 cm), or to some
limited-production tires.
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Tire Chains
{CAUTION:
Do not use tire chains. There is not
enough clearance. Tire chains used on a
vehicle without the proper amount of
clearance can cause damage to the
brakes, suspension, or other vehicle
parts. The area damaged by the tire
chains could cause you to lose control of
your vehicle and you or others may be
injured in a crash. Use another type of
traction device only if its manufacturer
recommends it for use on your vehicle
and tire size combination and road
conditions. Follow that manufacturer’s
instructions. To help avoid damage to
your vehicle, drive slowly, re-adjust or
remove the device if it is contacting your
vehicle, and do not spin your wheels.
If you do nd traction devices that will t,
install them on the rear tires.
Lifting Your Vehicle (CTS-V)
{CAUTION:
Lifting a vehicle can cause an injury.
The vehicle can slip off the jack and roll
over you or other people. You and they
could be badly injured. Find a level place
to lift your vehicle. To help prevent the
vehicle from moving:
1. Place the shift lever in REVERSE (R)
and rmly apply the parking brake.
2. Turn off the engine.
To be even more certain the vehicle will
not move, you can put blocks in front of
and behind the wheels. Also seeParking
Your Vehicle (Manual Transmission) on
page 132andParking Brake on page 128
for additional information.
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