2015 LEXUS RX450h Owners Manual

8166-1. Specifications
■ Tire dimensions
Section width
Ti r e h e i g h t
Wheel diameter
Tire section names
Bead
Sidewall
Shoulder
Tread
Belt
Inner liner
Reinforcing rubber
Carcass
Rim lines
Bead wires
Chafer

8176-1. Specifications
6
Vehicle specifications Uniform Tire Quality Grading
This information has b een prepared in accorda nce with regulations
issued by the National Highway Traf fic Safety Administration of the U.S.
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 an y questions you may have as you read
this information.
■ DOT quality grades
All passenger vehicle tires must co nform 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
■ Treadwear
The treadwear grade is a comparative rating based on the wear rate of
the tire when tested under controll ed 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 de pends 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.

8186-1. Specifications
■ 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 condit ions on specif ied 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 Mo tor 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 grades for this tire are established for a tire that
is properly inflated and not overloaded.
Excessive speed, underinflation, or excess ive loading, either separately or in
combination, can cause heat buildup and possible tire failure.

8196-1. Specifications
6
Vehicle specifications Glossary of tire terminology Tire related term Meaning
Cold tire inflation pres-
sure Tire 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-
sure The maximum cold inflated pressure to which a tire
may be inflated, shown on the sidewall of the tire
Recommended inflation
pressure Cold tire inflation pressure recommended by a man-
ufacturer
Accessory weight The combined weight (in excess of those standard
items which may be replaced) of hybrid 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 weight The weight of a motor vehicle with standard equip-
ment, including the maximum capacity of fuel, oil and
coolant, and if so equipp ed, 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
Normal occupant weight 150 lb. (68 kg) times the number of occupants speci-
fied in the second column of Table 1
* that follows

8206-1. Specifications
Tire related term Meaning
Occupant distribution Distribution 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 12-volt battery, and special trim
Rim A 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 designation Rim diameter and width
Rim type designation The industry manufacturer's designation for a rim by
style or code
Rim width Nominal 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 tire The 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 by two
We a t h e r s i d e The surface area of the rim not covered by the
inflated tire

8216-1. Specifications
6
Vehicle specifications Tire related term Meaning
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 separation A 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
Carcass The tire structure, except tread and sidewall rubber
which, when inflated, bears the load
Chunking The breaking away of pieces of the tread or sidewall
Cord The strands forming the plies in the tire
Cord separation The parting of cords from adjacent rubber com-
pounds
Cracking Any 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
Groove The space between two adjacent tread ribs
Innerliner The layer(s) forming the inside surface of a tubeless
tire that contains the inflating medium within the tire
Innerliner separation The parting of the innerliner from cord material in the
carcass

8226-1. Specifications
Tire related term Meaning
Intended outboard side-
wall (a) The sidewall that contains a whitewall, bears
white lettering, or bear s manufacturer, brand,
and/or model name molding that is higher or
deeper than the same molding on the other side-
wall 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
Light truck (LT) tire A tire designated by its manufacturer as primarily
intended for use on lightweight trucks or multipur-
pose passenger vehicles
Load rating The maximum load that a tire is rated to carry for a
given inflation pressure
Maximum load rating The load rating for a tire at the maximum permissible
inflation pressure for that tire
Maximum permissible
inflation pressure The maximum cold inflation pressure to which a tire
may be inflated
Measuring rim The rim on which a tire is fitted for physical dimension
requirements
Open splice Any parting at any junction of tread, sidewall, or
innerliner that extends to cord material
Outer diameter The overall diameter of an inflated new tire
Overall width The linear distance between the exteriors of the side-
walls of an inflated tire, including elevations due to
labeling, decorations, or protective bands or ribs
Passenger car tire A tire intended for use on passenger cars, multipur-
pose passenger vehicles, and trucks, that have a
gross vehicle weight rating (GVWR) of 10,000 lb. or
less.
Ply A layer of rubber-coated parallel cords

8236-1. Specifications
6
Vehicle specifications Tire related term Meaning
Ply separation A parting of rubber comp ound between adjacent
plies
Pneumatic tire A mechanical device made of rubber, chemicals, fab-
ric and steel or other mate rials, that, when mounted
on an automotive wheel, provides the traction and
contains the gas or fluid that sustains the load
Radial ply tire A pneumatic tire in which the ply cords that extend to
the beads are laid at substantially 90 degrees to the
centerline of the tread
Reinforced tire A tire designed to operate at higher loads and at
higher inflation pressures than the corresponding
standard tire
Section width The linear distance between the exteriors of the side-
walls of an inflated tire, excluding elevations due to
labeling, decoration, or protective bands
Sidewall That portion of a tire between the tread and bead
Sidewall separation The parting of the rubber compound from the cord
material in the sidewall
Snow tire A tire that attains a traction index equal to or greater
than 110, compared to the ASTM E-1136 Standard
Reference Test Tire, when using the snow traction test
as described in ASTM F-1805-00, Standard Test
Method for Single Wheel Driving Traction in a
Straight Line on Snow-and Ice-Covered Surfaces,
and which is marked with an Alpine Symbol (
)
on at least one sidewall
Te s t r i m The rim on which a tire is fitted for testing, and may be
any rim listed as appropriate for use with that tire