1993 Buick Riviera Owner's Manual - Page 248

When to Check: Check your tires once a month or more. Don't forget your compact spare tire. It shouldat 60 be psi (420 kPa). Tire Inspection and Rotation To make your tires last longer, have them inspected and in rotated at the mileages recommended the Maintenance, Schedule. See "Scheduled Maintenance Services" in the Index. How to Check: Use a good quality pocket-type gage to check tire pressure. Simply looking at the tires will not if -tell you the pressure, especially you have radial tires which may look properly inflated even if they're underinflated. If your tires have valve caps, be sure to put them back on. They help prevent leaks keeping out dirt and .by moisture. I r- Use this rotation pattern. After the tires have been rotated, adjust the front and rear inflation pressure shown on the Tire-Loading as Information label. Make certain that all wheel nuts are in properly tightened. See "Wheel Nut Torque" the Index.