wheel alignment SAAB 9-3 2009 Owners Manual

241
Car care
High speed operation
If you’ll be driving at high speeds, speeds of
100 mph (160 km/h) or higher, where it is
legal, set the cold inflation pressure to the
maximum inflation pressure shown on the
tire sidewall, or to 35 psi (244 kPa), which-
ever is lower. See the example below.
When you end this high-speed driving,
return to the cold inflation pressure shown
on the Tire and Loading Information label.
See on page 250.
Example
You’ll find maximum load and inflation pres-
sure molded on the tire’s sidewall, in small
letters near the rim flange. It will read some-
thing like this: Maximum load 690 kg
(1521 lbs) 300 kPa (44 psi) Max. Press
For this example, you would set the inflation
pressure for high-speed driving at 35 psi
(244 kPa).When to checkCheck your tires once a month or more.
Don’t forget your compact spare tire. It
should be at 60 psi (420 kPa).
How to CheckUse a good quality pocket-type gage to
check tire pressure. Yo u can’t tell if your
tires are properly inflated simply by looking
at them. Radial tires may look properly
inflated even when they’re underinflated.
Be sure to put the valve caps back on the
valve stems. They help prevent leaks by
keeping out dirt and moisture.Tire Inspection and RotationTires should be rotated every 10,000 miles
(16 000 km).
Any time you notice unusual wear, rotate
your tires as soon as possible and check
wheel alignment. Also check for damaged
tires or wheels. See “When It Is Time for
New Tires” on page 242 and “Wheel
Replacement” on page 246 for more infor-
mation.
The purpose of regular rotation is to achieve
more uniform wear for all tires on the vehi-
cle. The first rotation is the most important.
When rotating your tires, always use the
correct rotation pattern. Le ft front tire to left
rear. Left rear tire to right front. Right front to
right rear. Right rear to left front.
Don’t include the compact spare tire in your
tire rotation.
After the tires have b een rotated, adjust the
front and rear inflation pressures as shown
on the Tire-Loading Information label. Make
WARNING
Driving at high speeds, 100 mph
(160 km/h) or higher, puts an additional
strain on tires.
Sustained high-speed driving causes
excessive heat build up and can cause
sudden tire failure. You could have a
crash and you or others could be killed.
Some high-speed rated tires require infla-
tion pressure adjustment for high speed
operation. When speed limits and road
conditions are such that a vehicle can be
driven at high speeds, make sure the tires
are rated for high speed operation, in
excellent condition, and set to the correct
cold tire inflation pressure for the vehicle
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245
Car care
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 a half (1.5) times as well on the govern-
ment course as a tire graded 100. The rela-
tive 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 prac-
tices and differences in road characteristics
and climate.
Traction – AA, A, B, C
The traction grades, from highest to lowest,
are AA, A, B, and C. Those grades repre-
sent the tire’s ability to stop on wet pave-
ment as measured under controlled condi-
tions on specified government test surfaces
of asphalt and concrete. A tire marked C
may have poor traction performance. Warn-
ing: The traction grade assigned to this tire
is based on straight-ahead braking traction
tests, and does not include acceleration,
cornering, hydroplaning, or peak traction
characteristics. Temperature – A, B, C
The temperature grades are 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 material of the tire to degenerate
and reduce tire life, and excessive temper-
ature can lead to sudden tire failure. The
grade C corresponds to a level of perfor-
mance 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.
Warning: The temperature grade for this tire
is established for a tire that is properly
inflated and not overloaded. Excessive
speed, underinflation, or excessive loading,
either separately or in combination, can
cause heat buildup and possible tire failure.
Wheel Alignment and Tire
BalanceThe wheels on your vehicle were aligned
and balanced carefully at the factory to give
you the longest tire life and best overall per-
formance.
Scheduled wheel alignment and wheel bal-
ancing are not needed. However, if you
notice unusual tire wear or your vehicle pull-
ing one way or the other, the alignment may
need to be reset. If yo u notice your vehicle
vibrating when driving on a smooth road,
your wheels may need to be rebalanced.
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