2015 Lexus IS250 Owner's Manual

5289-1. Specifications
IS350/250_U (OM53C50U)
■Typical tire size information
The illustration indicates typical tire
size. Tire use (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 digits or 3 digits)
Speed symbol
(alphabet with one letter)
■Tire dimensions
Section width
Tire height
Wheel diameter
Ti re si ze
1
2
3
4
5
6
7
1
2
3

5299-1. Specifications
9
Vehicle specifications
IS350/250_U (OM53C50U)
Bead
Sidewall
Shoulder
Tr e a d
Belt
Inner liner
Reinforcing rubber
Carcass
Rim lines
Bead wires
Chafer
Tire section names
1
2
3
4
5
6
7
8
9
10
11

5309-1. Specifications
IS350/250_U (OM53C50U)
This information has been prepared in accordance with regulations issued by the
National Highway Traffic Safety Administration of the U.S. Department of Trans-
portation.
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 infor-
mation.
■DOT quality grades
All passenger vehicle 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
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 - 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.
Performance may differ significantly from the norm due to variations in driving
habits, service practices and differences in road characteristics and climate.
■Traction AA, A, B, C
The traction grades, from highest to lowest, are AA, A, B and C, and they rep-
resent 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 th is tire is based on braking (straight
ahead) traction tests and does not include cornering (turning) traction.
Uniform Tire Quality Grading

5319-1. Specifications
9
Vehicle specifications
IS350/250_U (OM53C50U)
■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 failure.
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 grades of a tire assume that it is properly inflated and
not overloaded.
Excessive speed, underinflation, or excessive loading, either separately or in com-
bination, can cause heat buildup and possible tire failure.

5329-1. Specifications
IS350/250_U (OM53C50U)
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 manu-
facturer
Accessory weight
The 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 weight
The 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
weight
The sum of:
(a) Curb weight
(b) Accessory weight
(c) Vehicle capacity weight
(d) Production options weight
Normal occupant weight150 lb. (68 kg) times the number of occupants specified
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 in stalled regular production
options weighing over 5 lb. (2.3 kg) in excess of the
standard items which they replace, not previously con-
sidered 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

5339-1. Specifications
9
Vehicle specifications
IS350/250_U (OM53C50U)
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 dis-
tributing 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 dis-
tributing to each axle its share of curb weight, accessory
weight, and normal occupant weight (distributed in
accordance with Table 1
* below), and dividing by two
We a t h e r s i d eThe surface area of the rim not covered by the inflated
tire
BeadThe 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 tireA 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 compounds
CrackingAny parting within the tread, sidewall, or innerliner of
the tire extending to cord material
Tire related termMeaning

5349-1. Specifications
IS350/250_U (OM53C50U)
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 tireA tire designed to operate at higher loads and at higher
inflation pressures than the corresponding standard tire
GrooveThe space between two adjacent tread ribs
InnerlinerThe layer(s) forming the inside surface of a tubeless tire
that contains the inflating medium within the tire
Innerliner separationThe parting of the innerliner from cord material in the
carcass
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 out-
ward when mounted on a vehicle
Light truck (LT) tireA tire designated by its manufacturer as primarily
intended for use on lightweight trucks or multipurpose
passenger vehicles
Load ratingThe maximum load that a tire is rated to carry for a given
inflation pressure
Maximum load ratingThe load rating for a tire at the maximum permissible
inflation pressure for that tire
Maximum permissible infla-
tion pressureThe maximum cold inflation pressure to which a tire may
be inflated
Measuring rimThe rim on which a tire is fitted for physical dimension
requirements
Open spliceAny parting at any junction of tread, sidewall, or inner-
liner that extends to cord material
Outer diameterThe overall diameter of an inflated new tire
Tire related termMeaning

5359-1. Specifications
9
Vehicle specifications
IS350/250_U (OM53C50U)
Overall widthThe linear distance between the exteriors of the side-
walls of an inflated tire, including elevations due to label-
ing, decorations, or protective bands or ribs
Passenger car tireA tire intended for use on passenger cars, multipurpose
passenger vehicles, and trucks, that have a gross vehicle
weight rating (GVWR) of 10,000 lb. or less.
PlyA layer of rubber-coated parallel cords
Ply separationA parting of rubber compound between adjacent plies
Pneumatic tire
A mechanical device made of rubber, chemicals, fabric
and steel or other materials, 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 substa ntially 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
SidewallThat portion of a tire between the tread and bead
Sidewall separationThe 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 Ref-
erence Test Tire, when using the snow traction test as
described in ASTM F-1805-00, Standard Test Method
for Single Wheel Driving Tract ion 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 mThe rim on which a tire is fitted for testing, and may be
any rim listed as appropriate for use with that tire
Tire related termMeaning