2008 Subaru Impreza Owner's Manual - Page 349

Maintenance and service 11-33 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 snowcovered 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 provides 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 monitoring 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 illuminate. 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/cm2) for every difference of 108F (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 outside temperatures when the temperature in the garage is 608F (15.68C). Example: Tire size: P205/55R16 89V and P205/ 50R17 88V Standard tire pressures: Front: 33 psi (230 kPa, 2.3 kgf/cm2) Rear: 32 psi (220 kPa, 2.2 kgf/cm2) Garage temperature: 608F (15.68C) Outside temperature Adjusted pressure [psi (kPa, kgf/cm2)] front 308F (−18C) 108F (−128C) 36 (250, 2.5) 38 (265, 2.65) rear 35 (240, 2.4) 37 (255, 2.55) 39 (270, 2.7) −108F (−238C) 40 (280, 2.8) If the low tire pressure warning light illuminates 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 - CONTINUED -