Porsche CARRERA GT-2004 Manual page 146

Uniform Tire Quality Grading
Quality grades can be found where applicable on
the tire sidewall between tread shoulder and max-
imum section width.
146
Practical Tips, Emergency Service
Example
All passenger car tires must conform to Federal
Safety Requirements in addition to these grades.
Treadwear
The treadwear grade is a comparative rating
based on the wear rate of the tire when tested un-
der controlled conditions on a specific govern-
ment 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 vari-
ations in driving habits, service practices and dif-
ferences 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 con-
trolled conditions on specified government test
surfaces of asphalt and concrete.
A tire marked C may have poor traction perfor-
mance.
Warning!
The traction grade assigned to this is based on
braking (straight-ahead) traction tests and does
not include cornering (turned) traction, accelera-
tion, hydroplaning or peak traction characteris-
tics.