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342 Vehicle Care
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 0353.
Vehicle Capacity Weight
:The number
of designated seating positions
multiplied by 68 kg (150 lbs) plus the
rated cargo load. See Vehicle Load
Limits 0215.
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's capacity weight and the
original equipment tire size and
recommended inflation pressure. See
“Tire and Loading Information Label”
under Vehicle Load Limits 0215.
Tire Pressure
Tires need the correct amount of air
pressure to operate effectively.
{Warning
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
.Poor handling
.Reduced fuel economy for
internal combustion engine
vehicles
.Reduced range for electric vehicles
Overinflated tires, or tires that have
too much air, can result in:
.Unusual wear
.Poor handling
.Rough ride
(Continued)
Warning (Continued)
.Needless damage from road
hazards
The Tire and Loading Information label
on the vehicle indicates the original
equipment tires and the correct cold
tire inflation pressures. The
recommended pressure is the minimum
air pressure needed to support the
vehicle's maximum load carrying
capacity.
For additional information regarding
how much weight the vehicle can carry,
and an example of the Tire and Loading
Information label, see Vehicle Load
Limits 0215. How the vehicle is loaded
affects vehicle handling and ride
comfort. Never load the vehicle with
more weight than it was designed to
carry.
When to Check
Check the pressure of the tires once a
month or more.
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Vehicle Care 351
Warning (Continued)
or paper towel can be used; however,
use a scraper or wire brush later to
remove all rust or dirt.
Lightly coat the inner diameter of the
wheel hub opening with wheel bearing
grease after a wheel change or tire
rotation to prevent corrosion or rust
build-up.
{Warning
Do not apply grease to the wheel
mounting surface, wheel conical
seats, or the wheel nuts or bolts.
Grease applied to these areas could
cause a wheel to become loose or
come off, resulting in a crash.
When It Is Time for New Tires
Factors, such as maintenance, temperatures,
driving speeds, vehicle loading, and road
conditions affect the wear rate of the tires.
Treadwear indicators are one way to tell
when it is time for new tires. Treadwear
indicators appear when the tires have only
1.6 mm (1/16 in) or less of tread remaining.
See Tire Inspection 0348 and
Tire Rotation 0349.
The rubber in tires ages over time. This also
applies to the spare tire, if the vehicle has
one, even if it is never used. Multiple factors
including temperatures, loading conditions,
and inflation pressure maintenance affect
how fast aging takes place. GM recommends
that tires, including the spare if equipped,
be replaced after six years, regardless of tread wear. To identify the age of a tire, use
the tire manufacture date, which is the last
four digits of the DOT Tire Identification
Number (TIN) molded into one side of the
tire sidewall. The last four digits of the TIN
indicate the tire manufactured date. The
first two digits represent the week and the
last two digits, the year. For example, the
third week of the year 2020 would have a
4-digit DOT date of 0320. Week 01 is the
first full week (Sunday through Saturday) of
each year.Vehicle Storage
Tires age when stored normally mounted on
a parked vehicle. Park a vehicle that will be
stored for at least a month in a cool, dry,
clean area away from direct sunlight to slow
aging. This area should be free of grease,
gasoline, or other substances that can
deteriorate rubber.
Parking for an extended period can cause
flat spots on the tires that may result in
vibrations while driving. When storing a
vehicle for at least a month, remove the
tires or raise the vehicle to reduce the
weight from the tires.
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356 Vehicle Care
Caution (Continued)
down until it stops. Driving too fast or
spinning the wheels with chains on will
damage the vehicle.
If a Tire Goes Flat
It is unusual for a tire to blow out while
driving, especially if the tires are maintained
properly. If air goes out of a tire, it is much
more likely to leak out slowly. But if there
ever is a blowout, here are a few tips about
what to expect and what to do:
If a front tire fails, the flat tire creates a
drag that pulls the vehicle toward that side.
Take your foot off the accelerator pedal and
grip the steering wheel firmly. Steer to
maintain lane position, and then gently
brake to a stop, well off the road,
if possible.
A rear blowout, particularly on a curve, acts
much like a skid and may require the same
correction as used in a skid. Stop pressing
the accelerator pedal and steer to straighten
the vehicle. It may be very bumpy and
noisy. Gently brake to a stop, well off the
road, if possible.
{Warning
Driving on a flat tire will cause
permanent damage to the tire.
Re-inflating a tire after it has been driven
on while severely underinflated or flat
may cause a blowout and a serious crash.
Never attempt to re-inflate a tire that has
been driven on while severely
underinflated or flat. Have your dealer or
an authorized tire service center repair or
replace the flat tire as soon as possible.
{Warning
Lifting a vehicle and getting under it to
do maintenance or repairs is dangerous
without the appropriate safety equipment
and training. If a jack is provided with
the vehicle, it is designed only for
changing a flat tire. If it is used for
anything else, you or others could be
badly injured or killed if the vehicle slips
off the jack. If a jack is provided with the
vehicle, only use it for changing a
flat tire.If a tire goes flat, avoid further tire and
wheel damage by driving slowly to a level
place, well off the road, if possible. Turn on
the hazard warning flashers. See
Hazard
Warning Flashers 0142.
If your vehicle is loaded at or near
maximum cargo capacity, it may be difficult
to fit the jack under the vehicle due to the
environment (shoulder slope, road debris,
etc.). Removal of some weight may improve
the ability to fit the jack under the vehicle
at the correct jacking location.
{Warning
Changing a tire can be dangerous. The
vehicle can slip off the jack and roll over
or fall causing injury or death. Find a
level place to change the tire. To help
prevent the vehicle from moving:
1. Set the parking brake firmly.
2. Shift the vehicle to P (Park).
3. For vehicles with four-wheel drive with an N (Neutral) transfer case
position, be sure the transfer case is
in a drive gear —not in N (Neutral).
(Continued)