2003 Saab 9-3 Owner's Manual - Page 162

162 Starting and driving Tires WARNING Check the tire pressure at least once a month and before long journeys. Underinflation can result in: • punctures • separation of the tire and tread • damage to the sidewalls • damage to the rims on poor roads • poor handling characteristics • premature tire wear • increased fuel consumption. Note: Low tire pressure also causes premature tire wear and increased fuel consumption. Tire pressure should match the current load and speed of the car (see page 245). The tire pressures given apply to cold tires, that is tires that are the same temperature as the outside air temperature. The tire pressure increases approximately 4 psi/27 kPa as the tires become warm (e.g. during highway driving). When the temperature of the tires changes by 50°F (10°C), the tire pressure will change 2 psi/13 kPa. Never reduce the pressure of a hot tire. If the tires are hot when you check them, only increase the pressure, if necessary. Underinflated tires wear more quickly than slightly overinflated tires. If a valve is leaking, simply unscrew it and fit a new one. Note: Remember to adjust the tire pressures if you change the load in the car significantly or intend to drive at substantially lower or higher speeds than normal. Automatic tire pressure monitoring, see page 207. Driving with a load The handling characteristics are affected by how the car is loaded. • Place the heaviest load as far forward and as low as possible in the trunk. • Secure the load to the lashing eyes (see page 118). • Heavy loads mean that the car's center of gravity is further back. As a result, the car will sway more during evasive steering. • Never exceed the permissible load of the roof box, even if there is room for more. • Ensure that the tire pressure is correct - slight overinflation is preferable to underinflation. • The braking distance of a loaded car is always greater. Keep your distance from the vehicle in front. • Do not exceed the car's permissible gross vehicle weight or axle load (see page 236). • Roof loads can negatively affect telecommunication.