2008 Lexus GX470 Owner's Manual

424
6-1. Specifications
Tire information
Ty p i c a l t i r e s y m b o l s
Tire size(→ P. 4 2 6 )
DOT and Tire Identification Number (TIN) (→P. 425)
Location of treadwear indicators (→ P. 3 3 6 )
Tire ply composition and materials
Plies are layers of rubber-coated parallel cords. Cords are the strands
which form the plies in a tire.
Radial tires or bias-ply tires
A radial tire has RADIAL on the sidewall. A tire not marked RADIAL is a
bias-ply tire.
TUBELESS or TUBE TYPE
A tubeless tire does not have a tube and air is directly filled in the tire. A
tube type tire has a tube inside the ti re and the tube maintains the air pres-
sure.
Load limit at maximum cold tire inflation pressure ( →P. 4 2 9 )
Maximum cold tire inflation pressure ( →P. 4 2 9 )
This means the pressure to which a tire may be inflated.
Uniform tire quality grading
For details, see “Uniform Tire Quality Grading” that follows.

425
6-1. Specifications
6
Vehicle specifications
Typical DOT and tire identification number (TIN)DOT symbol
*
Tire Identification Number (TIN)
Tire manufacturer’s identifica-
tion mark
Tire size code
Manufacturer’s optional tire
type code (3 or 4 letters)
Manufacturing week
Manufacturing year
*: The DOT symbol certifies thatthe tire conforms to applicable
Federal Motor Vehicle Safety
Standards.
Summer tire or all season tire (→ P. 3 4 0 )
An all season tire has “M+S” on the sidewall. A tire not marked “M+S” is a
summer tire.

426
6-1. Specifications
Tire size
■ Typical tire size information
The illustration indicates typical
tire size.
Ti r e u s e
(P = Passenger car,
T = Temporary use)
Section width (millimeters)
Aspect ratio
(tire height to section width)
Tire construction code
(R = Radial, D = Diagonal)
Wheel diameter (inches)
Load index (2 or 3 digits)
Speed symbol
(alphabet with one letter)
■ Tire dimensions
Section width
Ti r e h e i g h t
Wheel diameter

427
6-1. Specifications
6
Vehicle specifications
Tire section namesBead
Sidewall
Shoulder
Tr e a d
Belt
Inner liner
Reinforcing rubber
Carcass
Rim lines
Bead wires
Chafer
Uniform Tire Quality GradingThis information has been prepared in accordance with regulations
issued by the National Highway Traffic Safety Administration of the
U.S.A. Department of Transportation.
It provides the purchasers and/or prospective purchasers of Lexus vehi-
cles 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
All passenger vehicle tires must conform to Federal Safety Require-
ments 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

428
6-1. Specifications
■Treadwear
The treadwear grade is a comparative rating based on the wear rate of
the tire when tested under controlled conditions on a specified gov-
ernment test course.
For example, a tire graded 150 would wear one and a half (1 - 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 varia-
tions in driving habits, service practices and differences in road characteris-
tics and climate.
■Traction AA, A, B, C
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) trac-
tion.
■ Temperature A, B, C
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 fail-
ure.
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.

429
6-1. Specifications
6
Vehicle specifications
Warning: The temperature grades for this tire are 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.
Glossary of tire terminology
Tire related termMeaning
Cold tire inflation
pressureTire pressure when the vehicle has been parked for
three hours or more, or has not been driven more
than 1 mile or 1.5 km under that condition
Maximum inflation pres-
sureThe maximum cold inflated pressure to which a tire
may be inflated, shown on the sidewall of the tire
Recommended inflation
pressureCold tire inflation pressure recommended by a man-
ufacturer
Accessory weight
The combined weight (in excess of those standard
items which may be replaced) of automatic trans-
mission, power steering, power brakes, power win-
dows, power seats, radio and heater, to the extent
that these items are available as factory-installed
equipment (whether installed or not)
Curb weight
The weight of a motor vehicle with standard equip-
ment, including the maximum capacity of fuel, oil
and coolant, and if so equipped, air conditioning and
additional weight optional engine
Maximum loaded
vehicle weight
The sum of:
(a) Curb weight
(b) Accessory weight
(c) Vehicle capacity weight
(d) Production options weight

430
6-1. Specifications
Tire related termMeaning
Normal occupant weight150 lb. (68 kg) times the number of occupants spec-
ified in the second column of Table 1 that follows
Occupant distributionDistribution of occupants in a vehicle as specified in
the third column of Table 1* below
Production options
weight
The combined weight of installed regular production
options weighing over 5 lb. (2.3 kg) in excess of the
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
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 manufacturer’s designation for a rim by
style or code
Rim widthNominal distance between rim flanges
Vehicle capacity weight
(Total load capacity)The rated cargo and luggage load plus 150 lb. (68
kg) times the vehicle’s designated seating capacity
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 tire
The load on an individual tire that is determined by
distributing to each axle its share of curb weight,
accessory weight, and normal occupant weight (dis-
tributed in accordance with Table 1* below), and
dividing it by two

431
6-1. Specifications
6
Vehicle specifications
Tire related termMeaning
We a t h e r s i d eThe surface area of the rim not covered by the
inflated tire
Bead
The part of the tire that is made of steel wires,
wrapped or reinforced by ply cords and that is
shaped to fit the rim
Bead separationA breakdown of the bond between components in
the bead
Bias ply tire
A pneumatic tire in which the ply cords that extend
to the beads are laid at alternate angles substantially
less than 90 degrees to the centerline of the tread
CarcassThe tire structure, except tread and sidewall rubber
which, when inflated, bears the load
ChunkingThe breaking away of pieces of the tread or sidewall
CordThe strands forming the plies in the tire
Cord separationThe parting of cords from adjacent rubber com-
pounds
CrackingAny parting within the tread, sidewall, or innerliner
of the tire extending to cord material
CT
A pneumatic tire with an inverted flange tire and rim
system in which the rim is designed with rim flanges
pointed radially inward and the tire is designed to fit
on the underside of the rim in a manner that
encloses the rim flanges inside the air cavity of the
tire
Extra load tire
A tire designed to operate at higher loads and at
higher inflation pressures than the corresponding
standard tire