Subaru 2008 IMPREZA - Manual (Page 323)

Tires and wheels
& Types of tires
You should be familiar with type of tires
present on your vehicle.
The factory-fitted tires are all-season tires.
! All season tires
All season tires are designed to provide
an adequate measure of traction, handling
and braking performance in year-round
driving including snowy and icy road
conditions. However all season tires do
not offer as much traction performance as
winter (snow) tires in heavy or loose snow
or on icy roads.
All season tires are identified by
“ALL
SEASON ” and/or “M+S” (Mud & Snow) on
the tire sidewall.
! Summer tires
Summer tires are high-speed capability
tires best suited for highway driving under
dry conditions.
Summer tires are inadequate for driving
on slippery roads such as on snow-
covered or icy roads.
If you drive your vehicle on snow-covered
or icy roads, we strongly recommend the
use of winter (snow) tires.
When installing winter tires, be sure to
replace all four tires.
! Winter (snow) tires
Winter tires are best suited for driving on
snow-covered and icy roads. However
winter tires do not perform as well as
summer tires and all season tires on roads
other than snow-covered and icy roads.
& Tire pressure monitoring
system (TPMS) (if equipped)
The tire pressure monitoring system pro-
vides the driver with a warning message
by sending a signal from a sensor that is
installed in each wheel when tire pressure
is severely low. The tire pressure monitor-
ing system will activate only when the
vehicle is driven. Also, this system may
not react immediately to a sudden drop in
tire pressure (for example, a blow-out
caused by running over a sharp object).
If you adjust the tire pressures in a warm
garage and will then drive the vehicle in
cold outside air, the resulting drop in tire
pressures may cause the low tire pressure
warning light to come on. To avoid this
problem when adjusting the tire pressures
in a warm garage, inflate the tires to
pressures higher than those shown on the
tire placard. Specifically, inflate them by an
extra 1 psi (6.9 kPa, 0.07 kgf/cm
2 ) for
every difference of 10 8F (5.68C) between
the temperature in the garage and the
temperature outside. By way of example,
the following table shows the required tire
pressures that correspond to various out-
side temperatures when the temperature
in the garage is 60
8F (15.68C).
Example:
Tire size: P205/55R16 89V and P205/
50R17 88V
Standard tire pressures:
Front: 33 psi (230 kPa, 2.3 kgf/cm
2 )
Rear: 32 psi (220 kPa, 2.2 kgf/cm 2 )
Garage temperature: 60 8F (15.68C)
Outside
temperature
Adjusted pressure
[psi (kPa, kgf/cm 2 )]
front rear
30 8F (−18C) 36 (250, 2.5) 35 (240, 2.4)
10 8F (−128C) 38
(265, 2.65)
37
(255, 2.55)
−108F (−238C) 40 (280, 2.8) 39 (270, 2.7)
If the low tire pressure warning light
comes on when you drive the vehicle in
cold outside air after adjusting the tire
pressures in a warm garage, re-adjust the
tire pressures using the method described
above. Then, increase the vehicle speed
to at least 20 mph (32 km/h) and check to
see that the low tire pressure warning light
goes off a few minutes later. If the low tire
pressure warning light does not go off, the
tire pressure monitoring system may not
Maintenance and service
11-31
– CONTINUED –