Porsche Boxster 2006, Owner'S Manual

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Practical Tips, Emergency Service
Uniform Tire Quality Grading
Quality grades can be found where applicable on
the tire sidewall between tread shoulder and maxi-
mum section width.
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 va-
riations in driving habits, service practices and dif-
ferences in road characteristics and climate.