2005 Saab 9-3 Owner's Manual - Page 237

Car care When to check Check your tires once a month or more. Don't forget your compact spare tire. It should be at 60 psi (420 kPa). After the tires have been rotated, adjust the front and rear inflation pressures as shown on the Tire-Loading Information label. Make certain that all wheel nuts are properly tightened. See page 249. 235 Flat spotting All tires get hot, especially on long journeys or when the car is driven hard. After the car has been parked with hot tires and the tires have cooled down, a flat spot can form in the tire, where it is in contact with the ground. The same can occur if the car has not been moved for a long time. Flat spots can cause vibration that can be felt through the steering wheel, similar to that experienced when the wheels need balancing. Flat spots of this type disappear once the tires get hot again, usually after 10-15 miles (20-25 km) of driving at cruising speed. If the outdoor temperature is low it takes a longer distance. How to Check Use a good quality pocket-type gage to check tire pressure. You 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. WARNING Rust or dirt on a wheel, or on the parts to which it is fastened, can make wheel nuts become loose after a time. The wheel could come off and cause an accident. When you change a wheel, remove any rust or dirt from places where the wheel attaches to the vehicle. In an emergency, you can use a cloth or a paper towel to do this; but be sure to use a scraper or wire brush later, if you need to, to get all the rust or dirt off. See "Changing a tire" on page 248. Tire Inspection and Rotation Tires should be rotated every 7,500 miles (12 500 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 236 and "Wheel Replacement" on page 239 for more information. The purpose of regular rotation is to achieve more uniform wear for all tires on the vehicle. The first rotation is the most important. When rotating your tires, always use the correct rotation pattern. Left 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.