Tires are manufactured by bonding rubber to fabric plies and steel cords. Despite the anti-aging ingredients mixed into the rubber compounds, there is a realization that tires are perishable and a growing awareness that some tires (especially trailer tires) will age out before their treads will wear out.
For the most part, today’s tires deliver more miles and years of service than ever before. In the 1970s, typical bias-ply tires lasted less than 20,000 miles and were only expected to be in service for about two years. In the 1980s, early radial ply tires offered a treadwear expectancy of about 40,000 miles during four years of service. By the turn of the century, many long-life radial tires extended treadwear to about 60,000 miles during four or more years of service. Passenger car and light truck tire technology and American driving conditions in the past resulted in tire treads wearing out before the rest of the tire aged. That may not always be true of today’s even longer-lasting tires that are approaching 80,000 miles of treadwear.
How many years will tires last before aging out?
Unfortunately, it’s impossible to predict when tires should be replaced based on their calendar age alone. Properly stored tires that are protected from the elements and not mounted on a wheel, age very slowly before they are mounted and put into service. In our experience, when tires are properly stored and cared for, most street tires have a useful life in service of between six to ten years. While part of that time is spent as the tire travels from the manufacturing plant to the manufacturer’s distribution center, to the retailer and to you, the remainder is the time it spends on your vehicle.
“Environmental conditions like exposure to sunlight and coastal climates and poor storage and infrequent use accelerate the aging process. In ideal conditions, a tire may have a life expectancy that exceeds ten years from its date of manufacture. However, such conditions are rare. Aging may not exhibit any external indications and, since there is no non-destructive test to assess the serviceability of a tire, even an inspection carried out by a tire expert may not reveal the extent of any deterioration.”
The U.S. National Highway Traffic Safety Administration (NHTSA) and tire manufacturers are currently studying the many variables. Exposure to the elements (sun and atmospheric), regularity of use (frequent or only occasional), and the quality of care (maintaining proper inflation pressure, wheel alignment, etc.) will all influence the answer. So while tire life depends on the service conditions and the environment in which they operate, the difficult task remains how to identify all of the variables that influence a tire’s calendar age and attempt to quantify their influence.
Should you replace old tires even if their treads aren’t worn out?
No one is sure of how long tires will last because of the many variables. Heavily loaded tires on vehicles stored outdoors in sunny, scorching hot climates and only driven occasionally face some of the most severe service conditions and potentially have the shortest calendar lifespan. In contrast, lightly loaded tires on vehicles parked in garages and driven daily in moderate climates experience some of the least severe service conditions and potentially have the longest lifespan.
There is the influence of how well drivers maintain their tires (regular cleaning and pressure checks and periodic rotations and wheel alignments). How they use and/or abuse them (drive on them when overloaded or underinflated) and the possibility of irreversible damage from punctures, cuts, and impacts with potholes, curbs, and other road hazards. A tire’s original durability will be permanently compromised if uncared for, abused, or damaged.
Therefore, every tire’s life expectancy ultimately depends on the environment in which it operates and its service conditions. The difficult task remains to quantify tire life based on calendar age. Arbitrarily replacing tires prematurely based simply on age may result in tires being discarded before their time, contributing to increased operating costs and waste disposal and recycling concerns.
What is the best thing you can do to care for your tires?
Keeping tires properly inflated is probably the most significant action a driver can take to prevent tire failure. For example, driving a vehicle with a significantly underinflated tire can permanently damage the tire’s internal structure in ways invisible to external visual inspections. A U.S. National Highway Traffic Safety Administration (NHTSA) tire aging field study revealed that 30 percent of spare tires observed were significantly underinflated when first checked. Putting underinflated spare tires into service before properly inflating would greatly increase their risk of catastrophic tire failure. The inflation pressure of spare tires should be checked monthly along with the rest of the set.
Our experience has been that when properly stored and cared for, most street tires have a useful life in service of between six to ten years. While part of that time is spent as the tire travels from the manufacturing plant to the manufacturer’s distribution center, to the retailer, and to you, the remainder is the time it spends on your vehicle.
Share your experiences or other helpful information or questions in the comments.
