Page 212 of 584

2124-5. Using the driving support systems
IS350/250_U (OM53C50U)
●When driving on roads that are branching or merging
●When driving on a road surface that is wet du e to rain, previous rainfall, standing water,
etc.
●When the vehicle experiences strong up-and -down motion such as when driving on an
extremely rough road or on a seam in the pavement
●When headlight brightness at nighttime is reduced due to dirt on the lenses, or when
the headlights are misaligned
●When driving on winding roads or roads that are uneven
●When driving on rough or unpaved roads
■When changing the tires
Depending on the tires used, sufficient performance may not be maintainable.
■Warning messages for the LDA system
Warning messages are used to indicate a syst em malfunction or to inform the driver of
the need for caution while driving. ( P. 4 76 )
CAUTION
■Before using the LDA system
Do not rely solely on the LDA system. The LDA system does not drive the vehicle auto-
matically, nor does it reduce the amount of care you need to take. As such, the driver
must always assume full responsibility for understanding his/her surroundings, for
operating the steering wheel to correct the driving line, and for driving safely.
Inappropriate or negligent drivin g could lead to an accident.
■To avoid operating the LDA by mistake
Switch the LDA system off using the LDA switch when not in use.
■Situations unsuitable for LDA system
Do not use the LDA system in any of the following situations.
Otherwise, the system may not function correctly and could result in an accident.
●When driving with tire chains, a spare tire, or similar equipment
●When there are objects or structures along the roadside that might be misinterpreted
as lane markers (such as guardrails, a curb, reflector posts, etc.)
●When driving on snowy roads
●When pavement lane markers are difficult to see due to rain, snow, fog, sand dust, etc.
●When there are visible lines on the pavement from road repairs, or if the remains of
old lane markers are still visible on the road
●When driving on a road with lane closures due to maintenance, or when driving in a
temporary lane
Page 470 of 584

4708-2. Steps to take in an emergency
IS350/250_U (OM53C50U)
CAUTION
■If both the ABS and the brake system warning lights remain on
Stop your vehicle in a safe place immediately and contact your Lexus dealer. The vehi-
cle will become extremely unstable during braking, and the ABS system may fail, which
could cause an accident resulting in death or serious injury.
■When the electric power steering system warning light comes on
The steering wheel may become extremely heavy.
If the steering wheel becomes heavier than us ual when operating, hold firmly and oper-
ate using more force than usual.
■If the tire pressure warning light comes on
Be sure to observe the following precautions. Failure to do so could cause a loss of
vehicle control and result in death or serious injury.
●Stop your vehicle in a safe place as soon as possible. Adjust the tire inflation pressure
immediately.
●If the tire pressure warning light comes on even after tire inflation pressure adjust-
ment, it is probable that you have a flat tire. Check the tires. If a tire is flat, change it
with the spare tire and have the flat tire repaired by the nearest Lexus dealer.
●Avoid abrupt maneuvering and braking. If the vehicle tires deteriorate, you could lose
control of the steering wheel or the brakes.
■If a blowout or sudden air leakage should occur
The tire pressure warning system may not activate immediately.
Page 471 of 584

4718-2. Steps to take in an emergency
8
When trouble arises
IS350/250_U (OM53C50U)
CAUTION
■Maintenance of the tires
Each tire, including the spare (if provided), should be checked monthly when cold and
inflated to the inflation pressure recomm ended by the vehicle manufacturer on the
vehicle placard or tire inflation pressure la bel (tire and load information label). (If your
vehicle has tires of a different size than the size indicated on the vehicle placard or tire
inflation pressure label [tire and load in formation label], you should determine the
proper tire inflation pressure for those tires.)
As an added safety feature, your vehicle has been equipped with a tire pressure moni-
toring system (TPMS-tire pressure warning system) that illuminates a low tire pressure
telltale (tire pressure warning light) when on e or more of your tires is significantly
under-inflated. Accordingly, when the low ti re pressure telltale (tire pressure warning
light) illuminates, you should stop and check your tires as soon as possible, and inflate
them to the proper pressure. Driving on a significantly under-inflated tire causes the
tire to overheat and can lead to tire failure. Under-inflation also reduces fuel efficiency
and tire tread life, and ma y affect the vehicle’s handling and stopping ability.
Please note that the TPMS (tire pressure wa rning system) is not a substitute for proper
tire maintenance, and it is the driver’s resp onsibility to maintain correct tire pressure,
even if under-inflation has no t reached the level to trigger illumination of the TPMS low
tire pressure telltale (tire pressure warning light).
Your vehicle has also been equipped with a TPMS (tire pressure warning system) mal-
function indicator to indicate when the system is not operating properly. The TPMS
(tire pressure warning system) malfunction indi cator is combined with the low tire pres-
sure telltale (tire pressure warning light). When the system detects a malfunction, the
telltale will flash for approximately one minu te and then remain continuously illumi-
nated. This sequence will cont inue upon subsequent vehicle start-ups as long as the
malfunction exists. When the malfunction indicator is illuminated, the system may not
be able to detect or signal low tire pressure as intended.
TPMS (tire pressure warning system) malfun ctions may occur for a variety of reasons,
including the installation of replacement or alternate tires or wheels on the vehicle that
prevent the TPMS (tire pressure warning system) from functioning properly. Always
check the TPMS (tire pressure warning syst em) malfunction telltale after replacing one
or more tires or wheels on your vehicle to ensure that the replacement or alternate
tires and wheels allow the TPMS (tire pressure warning system) to continue to function
properly.
NOTICE
■To ensure the tire pressure warning system operates properly
Do not install tires with different specificatio ns or makers, as the tire pressure warning
system may not operate properly.
Page 486 of 584
4868-2. Steps to take in an emergency
IS350/250_U (OM53C50U)
●Stop the vehicle on a hard, flat surface.
●Set the parking brake.
●Shift the shift lever to P.
●Stop the engine.
●Turn on the emergency flashers. (P. 4 5 6 )
If you have a flat tire
Your vehicle is equipped with a spare ti re. The flat tire can be replaced with
the spare tire.
For details about tires: P. 4 2 3
CAUTION
■If you have a flat tire
Do not continue driving with a flat tire.
Driving even a short distance with a flat ti re can damage the tire and the wheel beyond
repair, which could result in an accident.
Before jacking up the vehicle
Page 487 of 584
4878-2. Steps to take in an emergency
8
When trouble arises
IS350/250_U (OM53C50U)
Location of the spare tire, jack and tools
Jack handle
Screwdriver
Wheel nut wrenchTowing eyelet
Spare tire
Jack1
2
3
4
5
6
Page 490 of 584
4908-2. Steps to take in an emergency
IS350/250_U (OM53C50U)
Remove the luggage mat.
Remove the spacer and tool tray.
Loosen the center fastener that
secures the spare tire.
If the center fastener cannot be turned
by hand, use the wheel nut wrench that
is stored in the trunk. (To secure the tire,
tighten the center fastener by hand. Do
not use the wrench or other tools.)
Taking out the spare tire
1
2
3
CAUTION
■When storing the spare tire
Be careful not to catch fingers or other body parts between the spare tire and the body
of the vehicle.
Page 493 of 584
4938-2. Steps to take in an emergency
8
When trouble arises
IS350/250_U (OM53C50U)
Remove any dirt or foreign matter
from the wheel contact surface.
If foreign matter is on the wheel contact
surface, the wheel nuts may loosen
while the vehicle is in motion, causing
the tire to come off.
Install the spare tire and loosely tighten each wheel nut by hand by approxi-
mately the same amount.
When replacing an aluminum wheel
with a steel wheel, tighten the wheel
nuts until the tapered portion comes
into loose contact with the disc
wheel seat.
Lower the vehicle.
Firmly tighten each wheel nut two or
three times in the order shown in the
illustration.
Tightening torque:
76 ft•lbf (103 N•m, 10.5 kgf•m)
Stow the flat tire, tire jack and all tools.
Installing the spare tire
1
2
Tapered portionDisc wheel
seat
3
4
5
Page 494 of 584

4948-2. Steps to take in an emergency
IS350/250_U (OM53C50U)
■The compact spare tire
●The compact spare tire is identified by the label “TEMPORARY USE ONLY” on the
tire sidewall.
Use the compact spare tire temporarily, and only in an emergency.
●Make sure to check the tire inflation pressure of the compact spare tire.
( P. 5 1 9 )
■When using the compact spare tire
As the compact spare tire is not equipped wi th a tire pressure warning valve and trans-
mitter, low inflation pressure of the spare ti re will not be indicated by the tire pressure
warning system. Also, if you replace the compact spare tire after the tire pressure warn-
ing light comes on, th e light remains on.
■When the compact spare tire is equipped
The vehicle becomes lower when driving with the compact spare tire compared to when
driving with standard tires.
■If you have a flat rear tire on a road covered with snow or ice (vehicles with front and
rear tires of the same size)
Install the compact spare tire on one of the front wheels of the vehicle. Perform the fol-
lowing steps and fit tire chains to the rear tires:
Replace a front tire with the compact spare tire.
Replace the flat rear tire with the tire removed from the front of the vehicle.
Fit tire chains to the rear tires.
1
2
3