1999 LEXUS SC300 Owners Manual

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367
Uniform tire quality grading
This information has been prepared in accordance with
regulations issued by the National Highway T raffic Safety
Administration of the U.S. Department of
Transportation. 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 information.
DOT quality grades ± All passenger vehicle tires must
conform to Federal Safety Requirements in addition to
these grades. These quality grades are molded on the
sidewall. 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 th eir use, however, and may depart 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 represent 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 this tire is based on
braking (straight ahead) traction tests and does not include
cornering (turning) traction.
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. The 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

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368required by law. Warning: The temperature grade of this tire established for a
tire that is properly inflated and not overloaded. Excessive
speed, underinflation, or excessive loading, either separately
or in combination, can cause heat buildup and possible tire
failure.
Tire selection
When replacing a tire, use only the same size and
construction as originally installed and with the same or
greater load capacity.
Using any other size or type of tire may seriously affect
handling, ride, speedometer/odometer calibration, ground
clearance, and clearance between the body and tires or snow
chains.
Do not mix radial, belted, or conventional tires on your
vehicle.
Do not use tires or wheels other than the manufacturer's
recommended size.
It can cause dangerous handling characteristics, resulting in
loss of control. If you need to change from conventional tires
to radial tires or vice versa, replace them as a set.

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369
INSTALLING SNOW TIRES ANDCHAINS
When to use snow tires or chains
Snow tires or chains are recommended when driving on
snow or ice.
On wet or dry road, conventional or radial tires provide better
traction than snow or studded tires.
Snow tire selection
If you need snow tires, select the same size, construction
and load capacity as the original tires on your Lexus.
Do not use tires other than stated above. 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 local regulations for possible
restrictions.
Snow tire installation
Snow tires should be installed on all wheels.
Installing snow tires on the rear wheels only can lead to an
excessive difference in road grip capability between the front
and rear tires which could cause loss of vehicle control.

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370
CAUTION
Snow tires should be inflated as described below, but never
above the maximum cold tire pressure shown on the tire
sidewall.
225/55R16 ... 220 kPa (2.2 kgf/cm
2 or bar, 32 psi)
 Never drive over 120 km/h (75 mph) with any type of snow
tires.
Tire chain selection
Regulations regarding the use of tire chains vary
according to location or type of road. Always check the
local regulations before installing chains.
Use SAE Class ºSº type radial tire chains, with the exception
of radial cable chains or V±bar type chains.
Chain installation
Install the chains on the rear tires as tightly as possible.
Do not use tire chains on the front tires. Retighten chains
after driving 0.5 ± 1.0 km (1/4 ± 1/2 mile).
When installing chains on your tires, carefully follow the
instructions of the chain manufacturer.

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371
CAUTION
Do not exceed 50 km/h (30 mph) or the chain
manufacturer's recommended speed limit, whichever is
lower.
 Drive carefully avoiding bumps, holes, and sharp turns,
which may cause the vehicle to bounce.
 Avoid sharp turns or locked±wheel braking, as use of
chains may adversely affect vehicle handling.

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372
REPLACING WHEELS
When to replace your wheels
If you have wheel damage such as bending, cracks or
heavy corrosion, the wheel should be replaced.
If you fail to replace damaged wheels, a tire may slip off a
wheel or they may cause loss of handling control.
Replacement with used wheels is not recommended as they
may have been subjected to rough treatment or high mileage
and could fail without warning. Also, bent wheels which have
been straightened may have hidden structural damage and
therefore should not be used. Never use an inner tube in a
leaking wheel which is designed for a tubeless tire.
Wheel selection
When replacing wheels, care should be taken to ensure
that they are equivalent to those rem oved in load capacity,
diameter, rim width, and offset.
Correct replacement wheels are available at your Lexus
dealer.
A wheel of a different size or type may adversely affect
handling, wheel and bearing life, brake cooling,
speedometer/odometer calibration, stopping ability,
headlight aim, bumper height, vehicle ground clearance, and
tire or snow chain clearance to the body and chassis.
ALUMINUM WHEEL PRECAUTIONS
After driving your vehicle the first 1600 km (1000 miles),
check that the wheel nuts are tight.
 If you have rotated, repaired, or changed your tires, check
that the wheel nuts are still tight after driving 1600 km
(1000 miles).
 When using tire chains, be careful not to damage the
aluminum wheels.
 Use only the Lexus wheel nuts and wrench designed for
your aluminum wheels.
 When balancing your wheels, use only Lexus balance
weights or equivalent and a plastic or rubber hammer.
 As with any wheel, periodically check your aluminum
wheels for damage. If damaged, replace immediately.

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373
SUSPENSION AND CHASSIS
CAUTION
Do not modify the suspension/chassis with lift kits, spacers,
springs, etc. It can cause dangerous handling characteristics,
resulting in loss of control.

SECTION 6 ± 4
374
SERVICE PROCEDURES AND
SPECIFICATIONS
Electrical components
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . \
.
374
Checking battery condition. . . . . . . . . . . . . . . . . . . . . . . . . . .
380
Battery recharging precautions . . . . . . . . . . . . . . . . . . . . . . . .
386
Checking and replacing the blade type fuses . . . . . . . . . . . . .
388
Checking the cartridge type fuses . . . . . . . . . . . . . . . . . . . . . .
393
Adding washer fluid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
396
Checking the headlight aim . . . . . . . . . . . . . . . . . . . . . . . . . .
396
Replacing light bulbs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
399
SPECIFICATIONS
±LOCATION OF FUSES