The tire industry has long recognized the consumers' role in the regular care and maintenance of their tires. The point at which a tire is replaced is a decision for which the owner of the tire is responsible. The tire owner should consider factors to include service conditions, maintenance history, storage conditions, visual inspections, and dynamic performance. The consumer should consult a tire service professional with any questions about tire service life. The following information and recommendations are made to aid in assessing the point of maximum service life.
What Factors Into The Service Life of a Tire?
Tires are designed and built to provide many thousands of miles of excellent service. For maximum benefit, tires must be maintained properly to avoid tire damage and abuse that may result in tire disablement. The service life of a tire is a cumulative function of the storage, stowing, rotation and service conditions, which a tire is subjected to throughout its life (load, speed, inflation pressure, road hazard injury, etc.). Since service conditions vary widely, accurately predicting the service life of any specific tire in chronological time is not possible.
The Consumer Plays an Important Role in Tire Maintenance
Tires should be removed from service for numerous reasons, including tread worn down to minimum depth, damage or abuse (punctures, cuts, impacts, cracks, bulges, underinflation, overloading, etc). For these reasons tires, including spares, must be inspected routinely, i.e., at least once a month. Regular inspection becomes particularly important the longer a tire is kept in service. If tire damage is suspected or found, General Tire recommends that the consumer have the tire inspected by a tire service professional. Consumers should use this consultation to determine if the tires can continue in service. It is recommended that spare tires be inspected at the same time. This routine inspection should occur whether or not the vehicle is equipped with a tire pressure monitoring system (TPMS).
Consumers are strongly encouraged to be aware of their tires' visual condition. Also, they should be alert for any change in dynamic performance such as increased air loss, noise or vibration. Such changes could be an indicator that one or more of the tires should be immediately removed from service to prevent a tire disablement. Also, the consumer should be the first to recognize a severe in-service impact to a tire and to ensure that the tire is inspected immediately thereafter.
Tire storage, stowage and rotation are also important to the service life of the tire. More information regarding proper storage, stowage and rotation is located in other General Tire publications, which are available upon request and through its websites.
Tire Service Life Recommendation
General Tire is unaware of any technical data that supports a specific tire age for removal from service. However, as with other members of the tire and automotive industries, General Tire recommends that all tires (including spare tires) that were manufactured more than ten (10) years previous be removed from service and be replaced with new tires, even when tires appear to be usable from their external appearance and if the tread depth may have not reached the minimum wear out depth.
Vehicle manufacturers may recommend a different chronological age at which a tire should be replaced based on their understanding of the specific vehicle application; General Tire recommends that any such instruction be followed. Consumers should note that most tires would have to be removed for tread wear-out or other causes before any proscribed removal period. A stated removal period in no way reduces the consumer's responsibility to replace tires as needed.
The Chronological Age of the Tires
The chronological age of any tire can be found on the tire sidewall by examining the characters following the symbol "DOT".
For tires manufactured after the year 1999, the last four numbers identify the date of manufacture of the tire to the nearest week. The first two of these four numbers identify the week of manufacture (which range from "01" to "52"). The last two numbers identify the year of manufacture (e.g., a tire with the information "DOT XXXXXX2703" was manufactured in the 27th week of 2003).
For tires manufactured prior to the year 2000, three numbers instead of four indicate the date of manufacture. Also, during the early 1990's, Continental added a triangle (◄) to the end of the character string to distinguish a tire built in the 1990's from previous decades (e.g., a tire with the information "DOT XXXXXX274◄" was manufactured in the 27th week of 1994).
Please note: This document supersedes PSIB 05 - 02.