As rubber ages, it loses elasticity, hardens and can become brittle. The reinforcing cords inside a tire can also deteriorate and lose strength. This increases the risk of a sudden tire failure the older the tire gets. After ten years, the risk of failure goes up sharply. Because of this, many safety experts say tires that are more than six years old have expired and should be replaced regardless of how much tread is left on the tires. 我去年底去Costco换冬胎，Costco就说我的胎太老了有裂纹，不安全，拒绝给我换上，虽然胎没有多少磨损，我还是买了新胎。
One of Canada's largest tire and auto repair retailers places no upper limit on the age of new tires it installs in customer vehicles.
While perfectly legal, because there are no expiry dates on tires, consumer safety experts say tires degrade over time and pose a potential risk.
“All of the science shows that tire age matters, tire age plays a role in the safety of the product whether or not it’s been used,” said Sean Kane of the Rehoboth, Massachusetts-based Safety, Research & Strategies.