Consumer Information - Mazda RX-7 1989 Owner's Manual

7. CONSUMER INFORMATION
67U7-0020E
UNIFORM TIRE QUALITY GRADING
The following information relates to the tire
grading system developed by the National
Highway Traffic Safety Administration wh ich
wi ll grade tires by treadwear, traction and
temperature performance:
TREAD WEAR
The treadwear grade is a comparative rat-
ing based on the wear rate of the tire when
tested under controlled cond itions on a
specified government test course. For exam-
ple, a tire graded 150 would wear one and
a half (1 ½) times as well on the government
course as a tire graded 100. The relative per-
formance of tires depends upon the actual
conditions of their use, however, and may
depart significantly from the norm due to var-
iations in driving habits, service practices
and differences in road characteristics and
climate.
671J7·0030E
TRACTION-A, B, C
The traction grades, from highest to lowest,
are A, B and C. These grades represent the
tire's ability to stop on wet pavement as
measu red under controlled conditions on
specified government test surfaces of as-
phalt and conc rete. A tire marked C may
have poor traction performance.
WARNING!
The traction grade assigned to th is ti re is
based on braking (straightahead) traction
tests and does not include cornering (turn-
ing) traction.
67U7 0040!:'
TEMPERATURE-A,B,C
The temperature grades of A (the highest),
B and C, representing the tire's resistance
to the generation of heat and its ability to dis-
sipate heat when tested under controlled
conditions on a specified indoor laboratory
test wheel. Sustained high temperature can
cause the materi al of the tire to degenerate
and reduce tire life, and excessive temper-
ature can lead to sudden ti re failure. The
grade C corresponds to a level of perform-
ance which all passenger vehicle tires must
meet under the Federal Motor Vehicle Safe-
ty Standard No. 109. Grades B and A rep-
resent higher levels ot performance on th e
laboratory test wheel than the minimum re-
quired by law.
7-1
WARNING!
The temperatu re grade for this tire is estab-
lished for a tire that is properly inflated and
not overloaded . Excessive speed, underin-
flation, or excessive loading, either separate-
ly or in combination, can cause heat buildup
and possible tire failure.