2004 Lexus GX470 Audio System / LEXUS 2004 GX470 THROUGH OCT. 2003 PROD. OWNER'S MANUAL (OM60A46U)

CHASSIS
538

1Section width
2Tire height
3Wheel diameter
Name of each section of tire

1Bead
2Sidewall
3Shoulder
4Tread
5Belt
6Inner liner
7Reinforcing rubber
8Carcass
9Rim lines
10Bead wires
11Chafer

CHASSIS
539
Uniform tire quality grading
This information has been prepared in accordance
with regulations issued by the National Highway
Traffic Safety Administration of the U.S.
Department of Transportation. It provides the
purchasers and/or prospective purchasers of
Lexus vehicles with information on uniform tire
quality grading.
Your Lexus dealer will help answer any questions
you may have as you read this information.
DOT quality grades Ð All passenger car tires must
conform to Federal Safety Requirements in
addition to these grades. 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
Treadwear Ð 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 a half (1 Ð 1/2) times as well 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 AA, A, B, C Ð The traction grades, from
highest to lowest, are AA, A, B and C, and they
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 this tire is
based on braking (straight ahead) traction tests and
does not include cornering (turning) traction.
Temperature A, B, C Ð The temperature grades are
A (the highest), B, and C, representing the tire's
resistance to the generation of heat and its ability to
dissipate heat when tested under controlled conditions
on a specified indoor laboratory test wheel. Sustained
high temperature can cause the material of the tire
to degenerate and reduce tire life, and excessive
temperature can lead to sudden tire failure. The
grade C corresponds to a level of performance which
all passenger car tires must meet under the Federal
Motor Vehicle Safety Standard No. 109. Grades B
and A represent higher levels of performance on the
laboratory test wheel than the minimum required by
law.
Warning: The temperature grade for this tire
established for a tire that is properly inflated and not
overloaded. Excessive speed, underinflation, or
excessive loading, either separately or in combination,
can cause heat buildup and possible tire failure.

CHASSIS
540
Tire related terms
Cold tire inflation
pressureTire inflation pressure when the vehicle has been parked at least 3 hours or
more, or it has not been driven more than 1.5 km or 1 mile under that condition
Maximum inflation
pressureThe maximum cold inflation pressure to which a tire may be inflated and shown
on the sidewall of the tire
Recommended
inflation pressureCold tire inflation pressure recommended by a manufacturer
Accessory weightThe combined weight (in excess of those standard items which may be replaced)
of automatic transmission, power steering, power brakes, power windows, power
seats, radio, and heater, to the extent that these items are available as
factory-installed equipment (whether installed or not)
Curb weightThe weight of a motor vehicle with standard equipment including the maximum
capacity of fuel, oil, and coolant, and, if so equipped, air conditioning and
additional weight optional engine
Maximum loaded
vehicle weightThe sum of Ð
(a) Curb weight;
(b) Accessory weight;
(c) Vehicle capacity weight; and
(d) Production options weight
Normal occupant
weight68 kg (150 lb.) times the number of occupants specified in the second column of
Table 1 that follows

CHASSIS
541
Production options
weightThe combined weight of those installed regular production options weighing over 2.3
kg (5 lb.) in excess of those standard items which they replace, not previously
considered in curb weight or accessory weight, including heavy duty brakes, ride
levelers, roof rack, heavy duty battery, and special trim
Vehicle capacity
weight
(Total load capacity)The rated cargo and luggage load plus 68 kg (150 lb.) times the vehicle's designated
seating capacity
Intended outboard
sidewall(a) The sidewall that contains a whitewall, bears white lettering or bears
manufacturer, brand, and/or model name molding that is higher or deeper
than the same molding on the other sidewall of the tire, or
(b) The outward facing sidewall of an asymmetrical tire that has a particular side
that must always face outward when mounted on a vehicle
Occupant distributionDistribution of occupants in a vehicle as specified in the third column of Table 1 that
follows
RimA metal support for a tire or a tire and tube assembly upon which the tire beads are
seated
Rim diameter (Wheel
diameter)Nominal diameter of the bead seat
Rim size designationRim diameter and width
Rim type designationThe industry of manufacturer's designation for a rim by style or code
Rim widthNominal distance between rim flanges

CHASSIS
542
Vehicle maximum load
on the tireThe load on an individual tire that is determined by distributing to each axle its share of
the maximum loaded vehicle weight and dividing by two
Vehicle normal load
on the tireThe load on an individual tire that is determined by distributing to each axle its share of
the curb weight, accessory weight, and normal occupant weight (distributed in
accordance with Table 1 that follows) and dividing by two
Weather sideThe surface area of the rim not covered by the inflated tire
Table 1 Ð Occupant loading and distribution for vehicle normal load for various designated seating
capacities
Designated seating capacity,
number of occupants
Vehicle normal load, number of
occupantsOccupant distribution in a
normally loaded vehicle
2 through 422 in front
5 through 1032 in front, 1 in second seat

CHASSIS
543
TYPES OF TIRES
Determine what kind of tires your vehicle is originally
equipped with.
1. Summer tires
Summer tires are high-speed capability tires best
suited to highway driving under dry conditions.
Since summer tires do not have the same traction
performance as snow tires, summer tires are
inadequate for driving on snow-covered or icy roads.
For driving on snow-covered or icy roads, we
recommend using snow tires. If installing snow tires,
be sure to replace all four tires.
2. All season tires
All season tires are designed to provide better traction
in snow and to be adequate for driving in most winter
conditions, as well as for use all year round.
All season tires, however, do not have adequate
traction performance compared with snow tires in
heavy or loose snow. Also, all season tires fall short
in acceleration and handling performance compared
with summer tires in highway driving.
The details about how to distinguish summer tires
from all season tires are described on page 535.
CAUTION
Do not mix summer and all season tires on
your vehicle as this can cause dangerous
handling characteristics, resulting in loss of
control.
Do not use tires other than the manufacturer's
designated tires, and never mix tires or
wheels of the sizes different from the
originals.

CHASSIS
544
ROTATING TIRES
To equalize tire wear and help extend tire life,
Lexus recommends that you rotate your tires
according to the maintenance schedule. (For
scheduled maintenance information, please refer
to the Owner's Manual Supplement/Scheduled
Maintenanceº.) However, the most appropriate
timing for tire rotation may vary according to your
driving habits and road surface conditions.
The wheel assemblies must be rotated as illustrated
above.
When rotating tires, check for uneven wear and
damage. Abnormal wear is usually caused by
incorrect tire pressure, improper wheel alignment,
out-of-balance wheels, or severe braking.Before storing radial, snow or studded tires, mark the
direction of rotation and be sure to install them in the
same direction when using them again. Tires should
be stored in a cool dry place.

CHASSIS
545
CHECKING AND REPLACING TIRES
When to replace your tires

1New tread2Tread wear indicator
3Worn tread
Replace the tires when the tread wear indicators
show. The location of the tread wear indicators
is shown by the marks molded on the sidewall of
each tire.
The tires on your Lexus have built-in tread wear
indicators to help you know when the tires need
replacement. When the tread depth wears to 1.6 mm
(0.06 in.) or less, the indicators will appear. If you
can see the indicators in two or more adjacent
grooves, the tire should be replaced.The effectiveness of snow tires is lost if the tread
wears down below 4 mm (0.16 in.).
If you have tire damage such as cuts, splits,
cracks deep enough to expose the fabric, or
bulges indicating internal damage, the tire should
be replaced.
If a tire often goes flat or cannot be properly repaired
due to the size or location of a cut or other damage,
it should be replaced. If you are not sure, consult
with your Lexus dealer.
If an air loss occurs while driving, do not continue
driving with a deflated tire. Driving even a short
distance can damage a tire beyond repair.
Any tires which are over 6 years old must be
checked by a qualified technician even if damage
is not obvious.
Tires deteriorate with age even if they have never or
seldom been used.
This also applies to the spare tire and tires stored
for future use.