Lexus SC 430 2004 Manual page 363

CHASSIS
The tires on your Lexus have built- in tread wear
indicators to help you know when the tires need
replacement. When the tread depth wears to 1.6 mm
(0.06 in.) or less, the indicators will appear. If you can
see the indicators in two or more adjacent grooves, the
tire should be replaced.
Your vehicle is equipped with 245/40ZR18 or
245/40ZR18 93Y tires: Your Lexus has been fitted with
specially developed tires which provide exceptional
dynamic performance under general road conditions.
However your riding comfort may worsen a little and
road noise may increase during driving. Riding comfort
and road noise with the run-flat tires may be a little
worse than that with the standard tires. You may also
notice that your tires will wear more rapidly and tire grip
performance will be reduced on the snowy and/or icy
roads when compared to high aspect ratio tires, etc. Be
sure to have snow tires or tire chains on the snowy
and/or icy roads and drive carefully with the speed
appropriate for road conditions.
344
NOTICE
Low profile tire like 245/40ZR18 or 245/40ZR18 93Y
may have greater damage than usual tires to its
tire wheel when receiving impact from the road
surface. Therefore, pay attention to the following.
D Be sure to use with proper tire inflation
pressure. If the tire inflation pressure is low, the
tire may have greater damage. For detailed
information about tire inflation pressure, see
page 326 or 329.
D Avoid driving onto high, sharp-edged objects
and other road hazards. Failure to do so can
lead to severe tire damage.
The effectiveness of snow tires is lost if the tread
wears down below 4 mm (0.16 in.).
If you have tire damage such as cuts, splits, cracks
deep enough to expose the fabric, or bulges
indicating internal damage, the tire should be
replaced.
If a tire often goes flat or cannot be properly repaired due
to the size or location of a cut or other damage, it should
be replaced. If you are not sure, consult with your Lexus
dealer.