Page 363 of 462

Black plate (51,1)Buick LaCrosse Owner Manual - 2011
Vehicle Care 10-51
(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
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 psi (pounds per
square inch) or kPa (kilopascal).
Accessory Weight
: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.
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
on page 10‑54.
Page 364 of 462

Black plate (52,1)Buick LaCrosse Owner Manual - 2011
10-52 Vehicle Care
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.
DOT Markings
:A code
molded into the sidewall of
a tire signifying that the tire
is in compliance with the U.S.
Department of Transportation
(DOT) Motor Vehicle Safety
Standards. The DOT code
includes the Tire Identification
Number (TIN), an alphanumeric
designator which can also
identify the tire manufacturer,
production plant, brand, and
date of production.
GVWR
:Gross Vehicle Weight
Rating. See Vehicle Load Limits
on page 9‑12. GAWR FRT
:Gross Axle
Weight Rating for the front axle.
See Vehicle Load Limits on
page 9‑12.
GAWR RR
:Gross Axle
Weight Rating for the rear axle.
See Vehicle Load Limits on
page 9‑12.
Intended Outboard Sidewall
:
The side of an asymmetrical tire,
that must always face outward
when mounted on a vehicle.
Kilopascal (kPa)
:The metric
unit for air pressure.
Light Truck (LT‐Metric) Tire
:A
tire used on light duty trucks and
some multipurpose passenger
vehicles.
Load Index
:An assigned
number ranging from 1 to 279
that corresponds to the load
carrying capacity of a tire. Maximum Inflation Pressure
:
The maximum air pressure to
which a cold tire can be inflated.
The maximum air pressure is
molded onto the sidewall.
Maximum Load Rating
:
The load rating for a tire at the
maximum permissible inflation
pressure for that tire.
Maximum Loaded Vehicle
Weight
:The sum of curb
weight, accessory weight,
vehicle capacity weight, and
production options weight.
Normal Occupant Weight
:
The number of occupants a
vehicle is designed to seat
multiplied by 68 kg (150 lbs).
See Vehicle Load Limits on
page 9‑12.
Occupant Distribution
:
Designated seating positions.
Page 366 of 462

Black plate (54,1)Buick LaCrosse Owner Manual - 2011
10-54 Vehicle Care
Vehicle Capacity Weight:
The number of designated
seating positions multiplied by
68 kg (150 lbs) plus the rated
cargo load. SeeVehicle Load
Limits on page 9‑12.
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 on
page 9‑12.
Tire Pressure
Tires need the correct amount
of air pressure to operate
effectively.
Notice: Neither tire
underinflation nor
overinflation is good.
Underinflated tires, or tires that do not have
enough air, can result in:
.Tire overloading and
over-heating which
could lead to a blowout.
.Premature or
irregular wear.
.Poor handling.
.Reduced fuel economy. Overinflated tires, or tires
that have too much air, can
result in:
.Unusual wear.
.Poor handling.
.Rough ride.
.Needless damage from
road hazards.
A vehicle-specific Tire and
Loading Information label
is attached to the vehicle.
This label shows the vehicle's
original equipment tires and the
correct inflation pressures for
the tires when they are cold.
The recommended cold tire
inflation pressure, shown on the
label, is the minimum amount of
air pressure needed to support
the vehicle's maximum load
carrying capacity.
Page 367 of 462

Black plate (55,1)Buick LaCrosse Owner Manual - 2011
Vehicle Care 10-55
For additional information
regarding how much weight
the vehicle can carry, and an
example of the Tire and Loading
Information label, seeVehicle
Load Limits on page 9‑12.
How you load the vehicle
affects vehicle handling and
ride comfort. Never load the
vehicle with more weight than
it was designed to carry.
When to Check
Check the tires once a month or
more. Do not forget to check the
compact spare tire, if the vehicle
has one. The compact spare
should be at 420 kPa (60 psi).
For additional information
regarding the compact spare
tire, seeCompact Spare Tire on
page 10‑85. How to Check
Use a good quality pocket-type
gauge to check tire pressure.
You cannot tell if the tires are
properly inflated simply by
looking at them. Radial tires
may look properly inflated even
when they are underinflated.
Check the tire's inflation
pressure when the tires are
cold. Cold means the vehicle
has been sitting for at least
three hours or driven no more
than 1.6 km (1 mi).
Remove the valve cap from the
tire valve stem. Press the tire
gauge firmly onto the valve to
get a pressure measurement.
If the cold tire inflation pressure
matches the recommended
pressure on the Tire and
Loading Information label,
no further adjustment is
necessary. If the inflation
pressure is low, add air until
you reach the recommended
amount.
If you overfill the tire, release air
by pushing on the metal stem
in the center of the tire valve.
Re‐check the tire pressure with
the tire gauge.
Be sure to put the valve caps
back on the valve stems. They
help prevent leaks by keeping
out dirt and moisture.
Page 375 of 462

Black plate (63,1)Buick LaCrosse Owner Manual - 2011
Vehicle Care 10-63
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 whenthe tires have only 1.6 mm (1/16 in)
or less of tread remaining. See
Tire
Inspection on page 10‑61 andTire
Rotation on page 10‑61 for more
information.
The rubber in tires ages over time.
This also applies for the spare tire,
if the vehicle has one, even if it is
never used. Multiple conditions
including temperatures, loading
conditions, and inflation pressure
maintenance affect how fast aging
takes place. Tires will typically
need to be replaced due to wear
before they may need to be
replaced due to age. Consult
the tire manufacturer for more
information on when tires should
be replaced.
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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