Aging Tire Defects
The structural integrity of a tire can degrade over an extended period of time. When that occurs, tires are more prone to catastrophic failure, which could, at best, cause an inconvenience, or, at worst, lead to a crash. The degradation of a tire occurs over time, mostly the result of a chemical reaction within the rubber components. That aging process can be accelerated by heat and sunlight.
NHTSA research suggests that tires age faster in warmer climates. Exposure to high ambient temperatures can accelerate the tire aging process, which could contribute to tire failures, including tread separations. Environmental conditions like exposure to sunlight and coastal climates, as well as poor storage and infrequent use can hasten the aging process.
Tire aging is generally not an issue with vehicles that are driven regularly. Tires will wear out and need to be replaced before aging becomes a safety concern. But those with occasional use - like recreational vehicles or collector cars, for example - could be susceptible. The spares on all vehicles also are prone to aging problems because they seldom get used or replaced. In those instances, the structural integrity of the tire may be weakened - and potentially hazardous - even though the tire still has a great deal of remaining tread.
The effects of aging may not be visibly detectable. Since there is no standard test to assess the serviceability of a tire, even an inspection performed by an expert may not always reveal the extent of tire deterioration. Vehicle owners are therefore encouraged to have their tires checked after five years of use, then annually thereafter.
How do you determine the age of a tire?
The age of the tire can be determined by checking the tire identification number on the sidewall of the tire, which begins with the letters "DOT". The last four digits represent the week and year the tire was manufactured. On newer model tires, the tire identification number is on the outside sidewall; older models will have the identification information on the inner sidewall.
When does NHTSA recommend that tires should be replaced?
While tire life will ultimately depend on the tires’ service conditions and the environment in which they operate, there are some general guidelines. Some vehicle manufacturers recommend that tires be replaced every six years regardless of use. In addition, a number of tire manufacturers cite 10 years as the maximum service life for tires. Check the owner’s manual for specific recommendations for your vehicle. Remember, it is always wise to err on the side of caution if you suspect your vehicle has tires that are over six years of age.
Defective tire are a significant safety problem.
Most failures result in nothing more serious than minor property damage. However, more than 11,000 tow-away crashes occur every year related to tire issues.