Giving a definitive expiration date on tires is no easy task. Tires carrying a heavy load or left outdoors in a desert-like environment with infrequent use are examples of the most severe service conditions. This will certainly shorten the lifespan of a tire. On the other hand, a tire that is driven only daily, garage parked and in a moderate climate will have the potential for the longest lifespan.
The tender loving care or lack thereof on behalf of the owner also contributes to tire life. Regular cleaning, air pressure checks and rotations and alignments all contribute to maximizing tire life. Some possible areas of neglect and abuse that will shorten the lifespan include overloading or running the tire underinflated. Road hazards such as potholes or curbs or other punctures, cuts and impacts can result in irreversible damage. A tire's durability can be compromised when abused or damaged.
This is why it is very difficult to determine the lifespan of a tire based on a calendar age. Tire Rack has found 6-10 years in service as being a reasonable expectation.
If you have more questions, feel free to contact your favorite sales specialist at Tire Rack for more information.