2004 Toyota Prius Owners Manual - Page 304

The tires on your Toyota have built−in tread wear indicators to help you know when the tires need replacement. When the tread depth wears to 1.6 mm (0.06 in.) or less, the indicators will appear. If you can see the indicators in two or more adjacent grooves, the tire should be replaced. The lower the tread, the higher the risk of skidding. The effectiveness of snow tires is lost if the tread wears down below 4 mm (0.16 in.). If you have tire damage such as cuts, splits, cracks deep enough to expose the fabric, or bulges indicating internal damage, the tire should be replaced. If a tire often goes flat or cannot be properly repaired due to the size or location of a cut or other damage, it should be replaced. If you are not sure, consult with your Toyota dealer. If air loss occurs while driving, do not continue driving. Driving even a short distance can damage a tire beyond repair. Any tires which are over 6 years old must be checked by a qualified technician even if damage is not obvious. Tires deteriorate with age even if they have never or seldom been used. This applies also to the spare tire and tires stored for future use. REPLACING YOUR TIRES When replacing a tire, use a tire of the same size and construction, and the same or greater load capacity as the originally installed tires. Using any other size or type of tire may seriously affect handling, ride, speedometer/odometer calibration, ground clearance, and clearance between the body and tires or snow chains. Check that the maximum load of the replaced tire is greater than 1/2 of the Gross Axle Weight Ratings (GAWR) of either the front axle or the rear axle, whichever is greater. As for the maximum load of the tire, see the load limit at maximum cold tire inflation pressure mentioned on the sidewall of the tire, and as for the Gross Axle Weight Ratings (GAWR), see the Certification Label. For details about the sidewall of the tire and the Certification Label, see pages 216 and 214. 292