1995 Buick Century Owner's Manual - Page 238

Don't include the compact spare tirein 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" in the Index. When it's Timefor New Tires One way to tell when it's time for new tires is to check the treadwear indicators, which will appear when your tires have only 1/16 inch (1.6 mm) or less of tread remaining. You need a new tire if You can see the indicators at three or more places around the tire. 0 You can see cord or fabric showing through the tire's rubber. The tread or sidewall is cracked, cut or snagged deep enough to show cord or fabric. The tire has a bump, bulge or split. 0 The tire has a puncture, cut, or other damage that can't be repaired well because of the size orlocation of the damage. 6-34