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422 Vehicle Care
Caution (Continued)
possible, avoid contact with
curbs, potholes, and other
road hazards.
Summer Tires
High Performance Summer
Tires
This vehicle may come
with may come with
245/40ZR19 94Y,
275/35ZR19 (100Y),
or 305/30ZR19 (102Y) high
performance summer tires.
These tires have a special
tread and compound that are
optimized for maximum dry
and wet road performance.
This special tread and
compound will have decreased
performance in cold climates,
and on ice and snow. It is
recommended that winter
tires be installed on the
vehicle if frequent driving at
temperatures below
approximately 5 °C (40 °F) oron ice or snow covered roads
is expected. See Winter Tires
0
419.
Caution
High performance summer
tires have rubber
compounds that lose
flexibility and may develop
surface cracks in the tread
area at temperatures below
−7 °C (20 °F). Always store
high performance summer
tires indoors and at
temperatures above −7 °C
(20 °F) when not in use. If the
tires have been subjected to
−7 °C (20 °F) or less, let them
warm up in a heated space
to at least 5 °C (40 °F) for
24 hours or more before
being installed or driving a
vehicle on which they are
installed. Do not apply heat
or blow heated air directly
on the tires. Always inspect
tires before use. See Tire
Inspection 0435.
Tire Sidewall Labeling
Useful information about a
tire is molded into its
sidewall. The example
shows a typical passenger
tire sidewall.
Passenger Tire Example
(1) Tire Size:The tire size
is a combination of letters
and numbers used to
define a particular tire's
width, height, aspect ratio,
construction type, and
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Cadillac CT5 Owner Manual (GMNA-Localizing-U.S./Canada-16500419) -
2023 - CRC - 5/6/22
424 Vehicle Care
Passenger (P-Metric) Tire
(1) Passenger (P-Metric)
Tire
:The United States
version of a metric tire
sizing system. The letter
"P" as the first character in
the tire size means a
passenger vehicle tire
engineered to standards
set by the U.S. Tire and Rim
Association.
(2) Tire Width
:The 3-digit
number indicates the tire
section width in millimeters
from sidewall to sidewall.
(3) Aspect Ratio
:A 2-digit
number that indicates the
tire height-to-width
measurements. For
example, if the tire size aspect ratio is 75, as
shown in item (3) of the
illustration, it would mean
that the tire's sidewall is
75 percent as high as it
is wide.
(4) 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.
(5) Rim Diameter
:
Diameter of the wheel in
inches.
(6) Service Description
:
These characters
represent the load index
and speed rating of the
tire. The load index
represents the load
carrying capacity a tire is
certified to carry. The speed rating is the
maximum speed a tire is
certified to carry a load.
Tire Terminology and
Definitions
Air Pressure:The amount
of air inside the tire
pressing outward on each
square inch of the tire. Air
pressure is expressed
in kPa (kilopascal) or psi
(pounds per square inch).
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.
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Cadillac CT5 Owner Manual (GMNA-Localizing-U.S./Canada-16500419) -
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440 Vehicle Care
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 tires, compact
spare tires, tires with
nominal rim diameters of
10 to 12 inches
(25 to 30 cm), or to some
limited-production tires.
While the tires available on
General Motors passenger
cars and light trucks may
vary with respect to these
grades, they must also
conform to federal safety
requirements andadditional General Motors
Tire Performance Criteria
(TPC) standards.
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
All Passenger Car Tires
Must Conform to Federal
Safety Requirements In
Addition To These 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 (1½) times aswell on the government
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.
Traction
The traction grades, from
highest to lowest, are AA,
A, B, and C. Those 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. Warning: The
traction grade assigned to
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Cadillac CT5 Owner Manual (GMNA-Localizing-U.S./Canada-16500419) -
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442 Vehicle Care
Each new wheel should have
the same load-carrying
capacity, diameter, width,
offset, and be mounted the
same way as the one it
replaces.
Replace wheels, wheel bolts,
wheel nuts, or Tire Pressure
Monitor System (TPMS)
sensors with new GM original
equipment parts.
{Warning
Using the wrong
replacement wheels, wheel
bolts, or wheel nuts can be
dangerous. It could affect
the braking and handling of
the vehicle. Tires can lose air
and cause loss of control,
resulting in a crash. Always
use the correct wheel, wheel
bolts, and wheel nuts for
replacement.
{Warning
Replacing a wheel with a
used one is dangerous. How
it has been used or how far
it has been driven may be
unknown. It could fail
suddenly and cause a crash.
When replacing wheels, use
a new GM original
equipment wheel.
Caution
The wrong wheel can also
cause problems with bearing
life, brake cooling,
speedometer or odometer
calibration, headlamp aim,
bumper height, vehicle
ground clearance, and tire or
tire chain clearance to the
body and chassis.
Tire Chains
{Warning
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
loss of control and a crash.
Use another type of traction
device only if its
manufacturer recommends
it for the vehicle's tire size
combination and road
conditions. Follow that
manufacturer's instructions.
To avoid vehicle damage,
drive slowly and readjust or
remove the traction device if
it contacts the vehicle. Do
not spin the wheels.(Continued)