The bias ply tires sold more than four decades ago were designed to provide no more than 20,000 miles of service and last no more than two years. Since then, tire manufacturers started bonding steel cords and fabric piles into the tire’s rubber to increase its durability and mileage. However, most consumers are unaware that every tire on their vehicle is perishable and its efficiency could expire long before the tire tread wears out, placing their life and every life sharing the roadway with them in jeopardy.
By the 1980s, radial tires had a significantly longer-lasting treadwear, providing 40,000 expected miles over four years. By the turn of the new millennium, drivers enjoyed even longer-lasting extended treadwear with a tire was designed to last for years or longer over 60,000 miles.
Today’s technology provides 80,000 miles or more of treadwear, meaning it can last much longer than the age of all other components inside the tire. While tire manufacturers are providing more value for consumers, the aging process and the tires’ treadwear durability might be providing a false sense of security if its remaining components begin breaking down before the tread wears out.
Exposure to Elements
Many studies have been conducted by tire manufacturers and the NHTSA (National Highway Traffic Safety Administration) in an effort to determine how long tires can perform optimally before breaking down. Recent studies indicate that exposure to atmospheric and solar elements play a significant role in minimizing tire efficiency as does regularity of use, proper maintenance and routine wheel alignments. Tire maintenance involves maintaining inflation pressure according to the manufacturer.
However, even though obvious factors including the effects of the environment and service condition can be used to calculate tire efficiency, the challenge remains in identifying every variable known to influence the calendar age of tires and when their efficiency expires. Currently, only tire industries outside of the U.S. are providing recommendations to inspect and replace vehicle tires that have reached their expiration. A June, 2001 issue of British Rubber Manufacturers Association recommends taking tires ten years and older out of service and not using any unused tire that is over six years old.
The Aging Process
Unfortunately, the aging process of tires may not be easily recognized by external indicators because the extent of deterioration is usually internal. Researchers know that the aging process of tires accelerates under specific environmental conditions that include infrequent use, poor storage, coastal climates and sunlight. Some tires may exceed the 10-year life expectancy, but only under the most ideal, rare conditions.
Recommended tire use practices published by Japan Automobile Tire Manufacturers Association (May 2005) encourage consumers to have their tires inspected professionally after providing five years of use. The inspection can determine if the vehicle’s tires, and spare tire, can provide additional years of safe service. However, after 10 years of use, even tires that appear usable should be replaced with an entire new set, including the spare.
Numerous European automobile manufacturers selling high-performance cars recommend replacing all tires six years or older. These recommendations are shortened because many European motorists and truckers travel under unusual motoring conditions such as diving at top speed on high-speed roadways including the German autobahn. While driving practices of the American public do not involve high-speed roadways many U.S. automobile manufacturers including General Motors, Ford Motor Company and Chrysler support the recommendations of European car companies to replace the original equipment tires on all vehicles after just six years of service.
It is crucial to note that there is a significant difference in the calendar age of original equipment tires and replacement tires. The calendar age of the tire actually begins on the date of its manufacture and not at the time the vehicle is purchased or new tires are installed.Automotive manufacturers typically mount wheels with new tires just before selling the vehicle. Alternatively, replacement tire companies, distributors and retailers can warehouse new tires for months or years before being mounted to the vehicle and placed into service.
When vehicles and tires are properly maintained, the useful life of a set of tires and service can last upwards of 6 to 10 years.