2008 Lexus IS250 tires

419
6-1. Specifications
6
Vehicle specifications
Type E
Ti r e s i z e
Front tires: 225/40R18 88Y
Rear tires: 255/40R18 95Y
Spare tire: T145/70R17 106M
Front and rear tire inflation pres-
sure
(Recommended cold tire inflation
pressure)
Driving under normal conditionsFront:
35 psi (240 kPa, 2.4 kgf/cm
2 or bar)*
Rear:
38 psi (260 kPa, 2.6 kgf/cm
2 or bar)*
Spare:
60 psi (420 kPa, 4.2 kgf/cm
2 or bar)
*: When driving at high speeds above 100 mph
(160 km/h), in countries where such speeds are
permitted by law, add 7.2 psi (50 kPa, 0.5 kgf/
cm
2 or bar) to the front tires and rear tires.
Never exceed the maximum cold tire inflation
pressure indicated on the tire sidewall.
Wheel size
Front wheels: 18  8J
Rear wheels: 18 8 1 /2J
Spare wheel: 17  4T
Wheel nut torque76 ft•lbf (103 N•m, 10.5 kgf•m)

425
6-1. Specifications
6
Vehicle specifications
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. 311)
Maximum cold tire inflation pressure ( P. 415)
This means the pressure to which a tire may be inflated.
Uniform tire quality grading
For details, see “Uniform tire quality grading” that follows.
Summer tire or all season tire ( P. 312)
An all season tire has “M+S” on the sidewall. A tire not marked “M+S” is a
summer tire.
“TEMPORARY USE ONLY” ( P. 387)
A compact spare tire is identified by the phrase “TEMPORARY USE
ONLY” molded into its sidewall. This tire is designed for temporary
emergency use only.

428
6-1. Specifications
■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.
■ 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 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.

429
6-1. Specifications
6
Vehicle specifications
■Temperature A, B, C
The temperature grades are A (the hi ghest), 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 build up and possible tire failure.
Glossary of tire terminology
Tire related termMeaning
Accessory weight
The combined weight (in excess of those standard
items which may be replaced) of automatic transmis-
sion, 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)
Cold tire inflation pres-
sureTire 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
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

441
6
Vehicle specifications
6-3. Initialization
Items to initialize
ItemWhen to initializeReference
Pow e r w i n d owAfter reconnecting or changing the
batteryP. 6 4
Engine oil maintenance
dataAfter changing engine oilP. 2 9 5
Tire pressure warning
system
• When rotating the tires differing with front and rear tire inflation pressures.
• When changing the tire inflation pressure by changing traveling
speed.
• When changing the tire size.
P. 3 0 7
The following item must be initialized for normal system operation in cases
such as after the battery is reconnected, or maintenance is performed on
the vehicle.

459
Alphabetical index
TachometerTacho indicator ....................................130
Tachometer ............................................130
Tail lights Switch ........................................................ 143
Talk switch*
Telephone switch*
Theft deterrent system Alarm ........................................................... 74
Engine immobilizer system .............. 72
Theft prevention labels .......................... 76
Tire inflation pressure........................... 316
Tire information Glossary ................................................ 429
Size ........................................................... 426
Tire identification number ............. 426
Uniform tire quality grading..........427
Tires Chains .......................................................183
Checking ............................................... 306
If you have a flat tire.......................... 382
Inflation pressure ................................. 316
Inflation pressure sensor................308
Information.............................................424
Replacing............................................... 382
Rotating tires ........................................ 306
Size ............................................................. 415
Snow tires................................................183
Tools .......................................................... 382
Total load capacity................................. 182 Towing
Dinghy towing ........................... 188, 189
Emergency towing........................... 350
Trailer towing ........................................ 187
TRAC.......................................................... 170
Traction control ...................................... 170
Transmission shift switches ................ 124
Trip meter ................................................. 130
Trunk Extending a space ............................ 258
Opener ........................................................ 41
Trunk light Trunk light ................................................. 42
Wattage ..................................................420
Turn signal lights Replacing light bulbs ........................ 342
Switch........................................................ 128
Wattage ..................................................420T
*: Refer to the “Navigatio n System Owner’s Manual”