Saab 1987 900 Owner's Manual page 66

64 Car care and scheduled maintenance
rate climates where snow and ice are not
too severe. Otherwise, winter tires should
be fitted for theses conditions.
The 195/65 R15 high performance tires
standard on all models with 16 valve engi-
nes have been developed to give the greatest
possible roadholding and stability under
both wet and dry driving conditions with
the result that the tread compounds and
designs are not suitable for use on ice and
snow. We therefore recommend winter
tires or "all weather" tires for these models
when driving on snow or ice. (See section
"Starting and driving" Winter driving.)
Replacement tires
Use only tires ofthe original size specifica-
tion load capacity and speed ratings. Speed
rating codes:
S = 110mph,max.
T = 118 mph, max.
H = 130 mph, max.
V= 130
+
mph
Tire rotation
The front-wheel drive causes the front and
rear tires to wear differently. In order to
maximize the overall tire tread life of wide
profile tires, such as those fitted as Saab ori-
ginal equipment, the tires should be
exchanged front to rear every 7,500 miles.
Make sure that the tires maintain the same
direction of rotation as before - i.e. the left
front wheel should only change place with
the left rear wheel and the right front wheel
should only change place with the right rear
wheel. After rotation, reset the front/rear
tire pressures according to the pressure
table in the Specifications section. Do not
change radial tires from side to side on the
car.
Tire quality grading
New tires must b e graded and labeled in
accordance with new Federal regulations.
Standard tests are conducted to measure
performance in the areas of traction and
temperature resistance. Refer to the tire
sidewall for the specific quality grades of
the tires provided on your new Saab. Com-
pact spare tires are exempt.
DOT QUALITY GRADES
Treadwear
Traction ABC
Temperature ABC
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 under controlled conditions on
a specified government test course. For
example, a tire graded 150 would wear one
and one half (11/2) 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
The traction grades, from highest to lowest,
are A, B, C, and they represent the tire's abi-
lity 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. Warning: The trac-
tion grade assigned to this tire is based on
braking (straightahead) traction tests and
does not include cornering (turning) trac-
tion.
Temperature
The temperature grades are A (the hig-
hest), B, and C, representing the tire's resis-
tance to the generation of heat and its abi-
lity to dissipate heat when tested under
controlled conditions on a specified indoor
laboratory test wheel. Sustained high tem-
perature can cause the material of the tire
to degenerate and reduce tire life, and
excessive temperature can lead to sudden
tire failure. The grade C corresponds to a
level of performance which all passenger
car tires must meet under the Federal
Motor Vehicle Safety Standard No. 109.
Grades B and A represent higher levels of
performance on the laboratory test wheel
than the minimum required by law. War-
ning: The temperature grade for this tire is
established for a tire that is properly infla-
ted and not overloaded. Excessive speed,
underinflation, or excessive loading, either
separately or in combination, can cause
heat buildup and possible tire failure.