2018 CADILLAC CT6 tire size

Cadillac CT6 Owner Manual (GMNA-Localizing-U.S./Canada-11292458) -
2018 - crc - 2/15/17
VEHICLE CARE 345
the tire size means a passenger
vehicle tire engineered to
standards set by the U.S. Tire and
Rim Association.
(2) Tire Width
:The three-digit
number indicates the tire section
width in millimeters from sidewall
to sidewall.
(3) 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 3 of
the illustration, it would mean
that the tire's sidewall is
60 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;
and the letter B means belted-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).
Accessory Weight
:The combined
weight of optional accessories.
Some examples of optional
accessories are automatic
transmission, 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 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 kPa (kilopascal) or psi (pounds
per square inch) before a tire has
built up heat from driving. See
Tire Pressure 0347.
Curb Weight
: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.

Cadillac CT6 Owner Manual (GMNA-Localizing-U.S./Canada-11292458) -
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placard.
SeeTire Pressure 0347 and Vehicle
Load Limits 0213.
Radial Ply Tire
:A pneumatic tire
in which the ply cords that extend
to the beads are laid at 90 degrees
to the centerline of the tread.
Rim
:A metal support for a tire
and upon which the tire beads are
seated.
Sidewall
:The portion of a tire
between the tread and the bead.
Speed Rating
:An alphanumeric
code assigned to a tire indicating
the maximum speed at which a
tire can operate.
Traction
:The friction between
the tire and the road surface. The
amount of grip provided.
Tread
:The portion of a tire that
comes into contact with the road.
Treadwear Indicators
:Narrow
bands, sometimes called wear
bars, that show across the tread of a tire when only 1.6 mm (1/16 in)
of tread remains. See
When It Is
Time for New Tires 0355.
UTQGS (Uniform Tire Quality
Grading Standards)
:A tire
information system that provides
consumers with ratings for a tire's
traction, temperature, and
treadwear. Ratings are determined
by tire manufacturers using
government testing procedures.
The ratings are molded into the
sidewall of the tire. See Uniform
Tire Quality Grading 0357.
Vehicle Capacity Weight
:The
number of designated seating
positions multiplied by
68 kg (150 lb) plus the rated cargo
load. See Vehicle Load Limits 0213.
Vehicle Maximum Load on the
Tire
:Load on an individual tire
due to curb weight, accessory
weight, occupant weight, and
cargo weight. Vehicle Placard
:A label
permanently attached to a vehicle
showing the vehicle capacity
weight and the original equipment
tire size and recommended
inflation pressure. See “Tire and
Loading Information Label” under
Vehicle Load Limits 0213.
Tire Pressure
Tires need the correct amount of
air pressure to operate effectively.
Caution
Neither tire underinflation nor
overinflation is good.
Underinflated tires, or tires that
do not have enough air, can
result in:
.Tire overloading and
overheating which could
lead to a blowout.
.Premature or
irregular wear.
(Continued)

Cadillac CT6 Owner Manual (GMNA-Localizing-U.S./Canada-11292458) -
2018 - crc - 2/15/17
VEHICLE CARE 349
Tire Pressure for
High-Speed Operation
{Warning
Driving at high speeds, 160 km/h
(100 mph) or higher, puts additional
strain on tires. Sustained
high-speed driving causes excessive
heat buildup and can cause sudden
tire failure. This could cause a
crash, and you or others could be
killed. Some high-speed rated tires
require inflation pressure
adjustment for high-speed
operation. When speed limits and
road conditions allow the vehicle to
be driven at high speeds, make sure
the tires are rated for high-speed
operation, are in excellent
condition, and are set to the correct
cold tire inflation pressure for the
vehicle load.
Gasoline only models with 235/
50R18 97V or 245/45R19 98V size
tires require inflation pressure
adjustment when driving the vehicle at speeds of 160 km/h (100 mph) or
higher. Set the cold inflation pressure
for all four tires to 270 kPa (39 psi).
Gasoline only models with 245/
40R20 95W size tires require inflation
pressure adjustment when driving the
vehicle at speeds of
160 km/h (100 mph) or higher. Set the
cold inflation pressure to
290 kPa (42 psi).
Gasoline only models with 245/
40ZR20 95Y size tires require inflation
pressure adjustment when driving the
vehicle at speeds of
160 km/h (100 mph) or higher. Set the
cold inflation pressure for the front
tires to 240 kPa (35 psi) and the rear
tires to 260 kPa (38 psi).
PLUG-IN models with 235/50R18 97V
and 265/45R18 101V size tires require
inflation pressure adjustment when
driving the vehicle at speeds of
160 km/h (100 mph) or higher. Set the
cold inflation pressure to 290
kPa (42 psi).
Return the tires to the recommended
cold tire inflation pressure when
high-speed driving has ended.
See
Vehicle Load Limits 0213 and Tire
Pressure 0347.Tire Pressure Monitor
System
The Tire Pressure Monitor System
(TPMS) uses radio and sensor
technology to check tire pressure
levels. The TPMS sensors monitor the
air pressure in your tires and transmit
tire pressure readings to a receiver
located in the vehicle.
Each tire, including the spare (if
provided), should be checked monthly
when cold and inflated to the
inflation pressure recommended by
the vehicle manufacturer on the
vehicle placard or tire inflation
pressure label. (If your vehicle has
tires of a different size than the size
indicated on the vehicle placard or tire
inflation pressure label, you should
determine the proper tire inflation
pressure for those tires.)

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A message to check the pressure in a
specific tire displays in the Driver
Information Center (DIC). The low tire
pressure warning light and the DIC
warning message come on at each
ignition cycle until the tires are
inflated to the correct inflation
pressure. Using the DIC, tire pressure
levels can be viewed. For additional
information and details about the DIC
operation and displays seeDriver
Information Center (DIC) 0162.
The low tire pressure warning light
may come on in cool weather when
the vehicle is first started, and then
turn off as the vehicle is driven. This
could be an early indicator that the air
pressure is getting low and needs to
be inflated to the proper pressure.
A Tire and Loading Information label,
attached to your vehicle, shows the
size of the original equipment tires
and the correct inflation pressure for
the tires when they are cold. See
Vehicle Load Limits 0213, for an
example of the Tire and Loading
Information label and its location.
Also see Tire Pressure 0347. The TPMS can warn about a low tire
pressure condition but it does not
replace normal tire maintenance. See
Tire Inspection
0353, Tire Rotation
0 353 and Tires 0340.
Caution
Tire sealant materials are not all
the same. A non-approved tire
sealant could damage the TPMS
sensors. TPMS sensor damage
caused by using an incorrect tire
sealant is not covered by the
vehicle warranty. Always use only
the GM approved tire sealant
available through your dealer or
included in the vehicle.
Factory-installed Tire Inflator Kits use
a GM approved liquid tire sealant.
Using non-approved tire sealants
could damage the TPMS sensors. See
Tire Sealant and Compressor Kit 0362
for information regarding the inflator
kit materials and instructions.
TPMS Malfunction Light and
Message
The TPMS will not function properly if
one or more of the TPMS sensors are
missing or inoperable. When the
system detects a malfunction, the low
tire pressure warning light flashes for
about one minute and then stays on
for the remainder of the ignition cycle.
A DIC warning message also displays.
The malfunction light and DIC
warning message come on at each
ignition cycle until the problem is
corrected. Some of the conditions that
can cause these to come on are:
. One of the road tires has been
replaced with the spare tire. The
spare tire does not have a TPMS
sensor. The malfunction light and
DIC message should go off after
the road tire is replaced and the
sensor matching process is
performed successfully. See “TPMS
Sensor Matching Process ”later in
this section.
. The TPMS sensor matching
process was not done or not
completed successfully after
rotating the tires. The malfunction

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The horn sounds twice to signal
the receiver is in relearn mode
and the TIRE LEARNING ACTIVE
message displays on the DIC
screen.
6. Start with the driver side front tire.
7. Place the relearn tool against the tire sidewall, near the valve stem.
Then press the button to activate
the TPMS sensor. A horn chirp
confirms that the sensor
identification code has been
matched to this tire and wheel
position.
8. Proceed to the passenger side front tire, and repeat Step 7.
9. Proceed to the passenger side rear tire, and repeat Step 7.
10. Proceed to the driver side rear tire, and repeat Step 7. The horn
sounds two times to indicate the
sensor identification code has
been matched to the driver side
rear tire, and the TPMS sensor
matching process is no longer active. The TIRE LEARNING
ACTIVE message on the DIC
display screen goes off.
11. Turn the vehicle off.
12. Set all four tires to the recommended air pressure level
as indicated on the Tire and
Loading Information label.
Tire Inspection
We recommend that the tires,
including the spare tire, if the
vehicle has one, be inspected for
signs of wear or damage at least
once a month.
Replace the tire if:
.The indicators at three or more
places around the tire can
be seen.
.There is cord or fabric showing
through the tire's rubber.
.The tread or sidewall is
cracked, cut, or snagged deep
enough to show cord or fabric.
.The tire has a bump, bulge,
or split.
.The tire has a puncture, cut,
or other damage that cannot
be repaired well because of the
size or location of the damage.
Tire Rotation
Tires should be rotated every
12 000 km/7,500 mi. See
Maintenance Schedule 0390.
Tires are rotated to achieve a
uniform wear for all tires. The first
rotation is the most important.
Anytime unusual wear is noticed,
rotate the tires as soon as
possible, check for proper tire
inflation pressure, and check for
damaged tires or wheels. If the
unusual wear continues after the
rotation, check the wheel
alignment.
See When It Is Time for New Tires
0 355 and Wheel Replacement
0 359.

Cadillac CT6 Owner Manual (GMNA-Localizing-U.S./Canada-11292458) -
2018 - crc - 2/15/17
354 VEHICLE CARE
Use this rotation pattern if the
vehicle has different size tires on
the front and rear.
Different tire sizes should not be
rotated front to rear.Use this rotation pattern when
rotating tires of the same size
installed on all four wheel
positions.
If the vehicle has a compact spare
tire, do not include it in the tire
rotation.
Adjust the front and rear tires to
the recommended inflation
pressure on the Tire and Loading
Information label after the tires
have been rotated.
SeeTire Pressure 0347 and Vehicle
Load Limits 0213. Reset the Tire Pressure Monitor
System. See
Tire Pressure Monitor
Operation 0350.
Check that all wheel nuts are
properly tightened. See “Wheel
Nut Torque ”under Capacities and
Specifications 0404.
{Warning
Rust or dirt on a wheel, or on the
parts to which it is fastened, can
make wheel nuts become loose
after time. The wheel could come
off and cause an accident. When
changing a wheel, remove any rust
or dirt from places where the wheel
attaches to the vehicle. In an
emergency, a cloth or a paper towel
can be used; however, use a scraper
or wire brush later to remove all
rust or dirt.
Lightly coat the center of the
wheel hub with wheel bearing
grease after a wheel change or tire
rotation to prevent corrosion or
rust build-up. Do not get grease

Cadillac CT6 Owner Manual (GMNA-Localizing-U.S./Canada-11292458) -
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performance, ride and handling,
traction control, and tire pressure
monitoring performance. GM's
TPC Spec number is molded onto
the tire's sidewall near the tire
size. If the tires have an all-season
tread design, the TPC Spec
number will be followed by MS for
mud and snow. SeeTire Sidewall
Labeling 0342, for additional
information.
GM recommends replacing worn
tires in complete sets of four.
Uniform tread depth on all tires
will help to maintain the
performance of the vehicle.
Braking and handling performance
may be adversely affected if all the
tires are not replaced at the same
time. If proper rotation and
maintenance have been done, all
four tires should wear out at
about the same time. See Tire
Rotation 0353 for information on
proper tire rotation. However, if it is necessary to replace only one
axle set of worn tires, place the
new tires on the rear axle.
Winter tires with the same speed
rating as the original equipment
tires may not be available for H, V,
W, and ZR speed rated tires. Never
exceed the winter tire's maximum
speed capability when using
winter tires with a lower speed
rating.
{Warning
Tires could explode during
improper service. Attempting to
mount or dismount a tire could
cause injury or death. Only your
dealer or authorized tire service
center should mount or
dismount the tires.
{Warning
Mixing tires of different sizes (other
than those originally installed on
the vehicle), brands, or types may
cause loss of control of the vehicle,
resulting in a crash or other vehicle
damage. Use the correct size, brand,
and type of tire on all four wheels.
{Warning
Using bias-ply tires on the
vehicle may cause the wheel rim
flanges to develop cracks after
many miles of driving. A tire
and/or wheel could fail suddenly
and cause a crash. Use only
radial-ply tires with the wheels
on the vehicle.
If the vehicle tires must be
replaced with a tire that does not
have a TPC Spec number, make
sure they are the same size, load

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range, speed rating, and
construction (radial) as the
original tires.
Vehicles that have a tire pressure
monitoring system could give an
inaccurate low-pressure warning if
non-TPC Spec rated tires are
installed. SeeTire Pressure Monitor
Operation 0350.
The Tire and Loading Information
label indicates the original
equipment tires on the vehicle.
See Vehicle Load Limits 0213.
Different Size Tires and
Wheels
If wheels or tires are installed that are
a different size than the original
equipment wheels and tires, vehicle
performance, including its braking,
ride and handling characteristics,
stability, and resistance to rollover
may be affected. If the vehicle has
electronic systems such as antilock
brakes, rollover airbags, traction control, electronic stability control,
or All-Wheel Drive, the performance
of these systems can also be affected.
{Warning
If different sized wheels are used,
there may not be an acceptable
level of performance and safety if
tires not recommended for those
wheels are selected. This increases
the chance of a crash and serious
injury. Only use GM specific wheel
and tire systems developed for the
vehicle, and have them properly
installed by a GM certified
technician.
See Buying New Tires 0355 and
Accessories and Modifications 0298.
Uniform Tire Quality
Grading
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 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 and additional
General Motors Tire Performance
Criteria (TPC) standards.