Uniform Tire Quality Grading - Lexus GS300 1998 Owner's Manual

CHASSIS
Vehicles equipped with 235/45ZR17 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. 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 standard tires. 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.
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.
If an air loss occurs while driving, do not continue driving
with a deflated tire. Driving even a short distance can damage
a tire beyond repair.
Any tires which are over 6 years old must be checked by
a qualified technician even if damage is not obvious.
Tires deteriorate with age even if they have never or seldom
been used.
This also applies to the spare tire and tires stored for future
use.
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Uniform tire quality grading

This information has been prepared in accordance with
regulations issued by the National Highway Traffic Safety
Administration of the U.S.
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 their 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 A, B, C – The traction grades, from highest to
lowest, are 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.
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