1997 Buick Regal Owner's Manual - Page 317

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. Tire Inspection and Rotation Tires should be rotated every 6,000 to 8,000 miles (10 000 to 13 000 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's Time for New Tires" and "Wheel Replacement" laterin this section 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. See "Scheduled Maintenance Services"in the Index for scheduled rotation intervals. When rotating your tires, always use the correct rotation pattern shown here. Don't include the compact spare tire in your tire rotation. 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 "Wheel Nut Torque" inthe Index.