Uniform Tire Quality Grading Standards (U.s. Vehicles) - Mercedes-Benz 2008 S550 Operator's Manual

Operation
Tires and wheels
Warning!
Never exceed the max. tire inflation
pressure. Follow recommended tire inflation
pressures.
Do not underinflate tires. Underinflated tires
wear excessively and/or unevenly, adverse-
ly affect handling and fuel economy, and are
more likely to fail from being overheated.
Do not overinflate tires. Overinflated tires
can adversely affect handling and ride com-
fort, wear unevenly, increase stopping dis-
tance, and result in sudden deflation
(blowout) because they are more likely to
become punctured or damaged by road de-
bris, potholes etc.
Uniform Tire Quality Grading Standards
(U.S. vehicles)
Tire manufacturers are required to grade
tires based on three performance
factors: treadwear, traction and
temperature resistance.
574
G
1 Treadwear
2 Traction
3 Temperature resistance
i
For illustration purposes only. Actual data
on tires are specific to each vehicle and may vary
from data shown in above illustration.
Quality grades can be found, where appli-
cable, on the tire sidewall between tread
shoulder and maximum section width. For
example:
Treadwear Traction Temperature
200 AA
All passenger car tires must conform to
federal safety requirements in addition to
these grades.
Treadwear
The treadwear grade is a comparative rat-
ing based on the wear rate of the tire when
tested under controlled conditions on a
specified government test course. For ex-
ample, a tire graded 150 would wear one
and one-half (1
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
The traction grades, from highest to low-
est, are AA, A, B, and C. Those grades rep-
resent the tire's ability to stop on wet
A
pavement as measured under controlled
conditions on specified government test
1
/ ) times as well on the
2