tire size Lexus GS450h 2007 Using the hands-free system (for cellular phone) / LEXUS 2007 GS450H THROUGH JUNE 2006 PROD. OWNER'S MANUAL (OM30727U)

157
2-4. Using other driving systems
2
When driving
NOTICE
■When using intuitive parking assist
In the following situations, the system may not function correctly due to a sensor
malfunction etc. Have the vehicle checked by your Lexus dealer.
• A beep does not sound when you turn the main switch ON.
• The intuitive parking assist operation display flashes, and a beep sound when
no obstacle has been detected.
• If the area around a sensor collides with something, or is subjected to strong impact.
• If the bumper collides with something.
• If the display shows continuously without a beep.
■When changing tires
If you install tires of a size other than that recommended by the manufacturer, the
system will be unable to correctly detect steering wheel movement. Always use tire
sizes recommended by the manufacturer.
■When washing the vehicle
When washing the vehicle using high pressure cleaning equipment, do not spray
water directly on the sensors. Subjecting the sensors to high pressure impact may
cause a malfunction.

166
2-4. Using other driving systems
CAUTION
■The hill-start assist control may not operate effectively when
●On steep inclines.
●On icy surfaces.
■When the VSC is activated
The slip indicator light flashes and a warning buzzer sounds. Always drive carefully.
Reckless driving may cause an accident. Exercise particular care when the indica-
tor light flashes and a buzzer sounds.
■Replacing tires
Make sure that all tires are of the same size, brand, tread pattern and total load
capacity. In addition, make sure that the ti res are inflated to the specified tire pres-
sure level.
The ABS and VSC will not function correctly if different tires are fitted on the vehi-
cle. 
Contact your Lexus dealer for further info rmation when replacing tires or wheels.
■Handling of tires and suspension
Using tires with any kind of problem or modifying the suspension will affect the
VDIM, and may cause the system to malfunction.

174
2-5. Driving information
Winter driving tips
Carry out the necessary preparations and inspections before driving the
vehicle in winter. Always drive the vehicle in a manner appropriate to the
prevailing weather conditions.
■ Pre-winter preparations
●Use fluids that ar
e appropriate to the prevailing outside tempera -
tures.
• Engine oil
• Engine/inverter coolant
• Washer fluid
● Ha
ve a service technician inspect th e level and specific gravity of
battery electrolyte.
● Ha
ve the vehicle fitted with four snow tires or purchase a set of
tire chains for the rear tires.
Ensure that all tires are the same si ze and brand, and that chains match
the size of the tires.
● Tire inflation pressure falls in winter as the outside temperature
falls. Add 2.8 to 4.3 psi (20 to 30 kPa, 0.2 to 0.3 kgf/cm2 or bar)
to the standard tire inflation pressure.

177
2-5. Driving information
2
When driving
To retract positionLower the wipers by pressing on
the upper par
t of the hook section.
■Snow chain installation
Observe the following precautions when installing and removing chains.
●Install and remove tire chains in a safe location.
●Install tire chains on the rear tires.
●Install tire chains following the inst ructions provided in the accompanying
instructions.
CAUTION
■Driving with snow tires
Observe the following precautions to reduce the risk of accidents. 
Failing to do so may result in a loss of vehicle control and cause death or serious
injury.
●Use tires of the size specified for your vehicle.
●Maintain the specified level of tire inflation pressure.
●Do not drive in excess of 75 mph (120 km/h), regardless of the type of snow tires
being used.
●Snow tires should be installed on all wheels.

377
4-3. Do-it-yourself maintenance
4
Maintenance and care
Initializing the tire pressure warning system
■The tire pressure warning system must be initialized in the following
circumstances:
● When r
otating the tires on vehicles differing with front and rear tire
inflation pressures.
● When changing the tir
e inflation pressure by changing traveling
speed or load weight, etc.
● When changing the tir
e size.
When the tire pressure warning sys tem is initializ
ed, the current tire
inflation pressure is set as the pressure benchmark.
■ Ho
w to initialize the tire pressure warning system
Park the vehicle in safe place and turn the po
wer switch to “OFF”
mode.
While the vehicle is moving, initialization is not performed.
Adjust the tire inflation pressure to the specified cold tire inflation
pressure level. ( P. 4 8 7 )
Make sure to adjust the tire pressure to the specified cold tire inflation
pressure level. The tire pressure warning system will operate based on
this pressure level.
Turn the power switch to “IG-ON” mode.
STEP1
STEP2
STEP3

379
4-3. Do-it-yourself maintenance
4
Maintenance and care
■Selecting ID codes
When replacing tires, make sure to select the ID code set that matches
the ne
w tire set. If the incorrect ID code is selected, the tire pressure
warning system will not operate properly. After a certain period of
time, the tire pressure warning li ght comes on after blinking for 1
minute to indicate a system malfunction.
“MAIN”
“2nd”
■When to replace your vehicle’s tires
Tires should be replaced if:
●You have tire damage such as cuts, splits, cracks deep enough to expose the
fabric or bulges indicating internal damage
●A tire goes flat repeatedly or cannot be properly repaired due to the size or
location of a cut or other damage
If you are not sure, consult with your Lexus dealer.
■Tire life
Any tire over 6 years old must be checked by a qualified technician even if they
h
ave seldom or never been used or damage is not obvious.
■If the tread wears down below 0.16 in. (4 mm) on snow tires
The effectiveness of snow tires is lost.
■Low profile tires (245/40R18, P245/40R18 and 245/40ZR18 tires)
Generally, low profile tires will wear more rapidly and tire grip performance will be
r
educed on snowy and/or icy roads when co mpared to standard tires. Be sure to
use snow tires or snow chains on snowy and/or icy roads and drive carefully at a
speed appropriate for road and weather conditions.

380
4-3. Do-it-yourself maintenance
■Maximum load of tire
Check that the maximum load of the replaced tire is greater than 1 /2 of the Gross
Axle Weight Ratings (GAWR) of either the front axle or the rear axle, whichever is
greater. 
As for the maximum load of the tire, see the load limit at maximum cold tire inflation
pressure mentioned on the sidewall of the tire, and as for the Gross Axle Weight
Ratings (GAWR), see the Certification Label. (
P. 385, 492).
■Tire types
1 Summer tires
Summer tires are high-speed performance tires best suited to highway driving
under dry conditions. Since summer tires do not have the same traction perfor-
mance as snow tires, summer tires are in adequate for driving on snow-covered
or icy roads. For driving on snow-covered roads or icy roads, the use of snow tires
is recommended. When 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 ade-
quate for driving in most winter conditions , as well as for use year round. All sea-
son tires, however, do not have adequa te traction performance compared with
snow tires in heavy or loos e snow. Also, all season tires fall short in acceleration
and handling performance compared with summer tires in highway driving.
3Snow tires For driving on snow-covered roads or icy roads, we recommend using snow tires.
If you need snow tires, select tires of the same size, construction and load capac-
ity as the originally installed tires. Since your vehicle has radial tires as original
equipment, make sure your snow tires also have radial construction. Do not install
studded tires without first checking loca l regulations for possible restriction.
Snow tires should be installed on all wheels. ( P. 1 74 )
■Initializing the tire pressure warning system
Initialize the tires with the tire inflatio n pressure adjusted to the specified level.

383
4-3. Do-it-yourself maintenance
4
Maintenance and care
CAUTION
■When inspecting or replacing tires
Observe the following precautions to prevent accidents. Failure to do so may cause
damage to parts of the drive train, as well as dangerous handling characteristics,
which may lead to fatal or injury accidents.
●Do not mix tires of different makes, models, tread patterns or tread wear.
●Do not use tire sizes other than those recommended by Lexus.
●Do not mix radial, bias-belted, or bias-ply tires.
●Do not mix summer, all season and winter tires.
■When initializing the tire pressure warning system
Do not push the reset switch without first ad justing the tire inflation pressure to the
specified level. Otherwise, the tire pressure warning light may not come on even if
the tire inflation pressure is low, or it may come on when the tire inflation pressure is
actually normal.
NOTICE
■Repairing or replacing tires, wheels and tire pressure warning valves and trans-
mitters
●When removing or fitting the wheels, tires or the tire pressure warning valve and
transmitter, contact your Lexus dealer as the tire pressure warning valve and
transmitter may be damaged if not handled correctly.
●When replacing tires, make sure also to replace the tire pressure warning valve
and transmitter grommets.
■Do not use puncture sealant sprays to repair flats
Puncture sealant sprays may damage tire pressure tire pressure warning valves and
transmitters.

385
4-3. Do-it-yourself maintenance
4
Maintenance and care
Tire inflation pressure
■Tire inflation pressure
The recommended cold tire inflation pressure and tire size is dis-
played on the tire and loading information label. ( P. 4 8 7)

389
4-3. Do-it-yourself maintenance
4
Maintenance and care
Wheels
■When replacing wheels
The wheels of your Lexus are equipped with tire pressure warning valves and trans-
mitters that allow the tire pressure warning system to provide advanced warning in
th
e event of a loss in tire inflation pressu re. Whenever wheels are replaced, the tire
pressure warning valves and transmitters must be switched over from the old
wheels. ( P. 3 76 )
If a wheel is bent, cracked or heavily corroded, it should be replaced. 
Otherwise, the tire may separate from
the wheel or cause loss of handling
control.
■ Wheel selection
When replacing wheels, care should be taken to ensure that they
ar

e equivalent to those removed in load capacity, diameter, rim
width, and offset.
Replacement wheels are available at your Lexus dealer.
Lexus does not recommend using:
• Wheels of different sizes or types
• Used wheels
• Bent wheels that have been straightened
• Lexus wheels with after market chrome plating
■ Aluminum wheel pr
ecautions
● Use only L
exus wheel nuts and wr enches designed for use with
your aluminum wheels.
● When r
otating, repairing or changi ng your tires, check that the
wheel nuts are still tight after driving 1000 miles (1600 km).
● Be car
eful not to damage the aluminum wheels when using tire
chains.
● Use only L
exus genuine balance weights or equivalent and a
plastic or rubber hammer when balancing your wheels.