Tire Aging

When a tire is built, the manufacturer fuses together rubber, steel, nylon, and other components in a giant pressure cooker. The finished tires are inspected and stored in a warehouse adjacent to the factory, and then shipped across the nation and the world to distribution centers where they sit until ordered by retailers. At the stores they might be installed immediately, or they might sit on the shelf for a few months waiting for a new owner. When they are eventually and mounted onto your car. The result is that due to logistics, a tire may take anywhere from a few months to a few years (for less popular sizes) to get through this warehousing process. We typically receive tires that are 4 to 6 months old, but it’s not uncommon to see tires that are two years old when we receive them. When we receive tires that look inordinately old, we’ll check the DOT codes to determine the age of the tire and return to the distributor any tire that is over 2 years old. We want you to have the freshest tires possible.

Tire Aging & Replacement Policy

As you drive on your tires, you’ll of course be able to notice the tire wearing down over time. What you won’t be able to notice is that the molecular bonds that hold together the rubber, steel, and nylon components will deteriorate over time due to exposure to heat, oxidation, UV rays, water vapor, etc… The harsher the environment, the faster these bonds will break down, eventually leading to the tire’s failure. For this reason, there is no way to tell exactly when a tire should be pulled out of service, but in NHTSA data indicates that tires become much more likely to catastrophically fail once they are over 10 years old. Based on this and the latest available science, Suburban Tire’s policy regarding tire aging and replacement is as follows:

Suburban tire will “suggest” replacing a tire once the tread depth is 5/32nds of an inch, and will “recommend” replacement at 4/32nds or less, due to significantly increased stopping distances in wet weather conditions as a tire’s tread wears down. In the automotive industry, the term suggest means that we think you should replace the tires or part soon. When we use the term recommend, that means you should replace the tires or parts now.
Tires over 10 years old should be taken out of service no matter the depth of the tread, as 10 years old tires are much more likely to catastrophically fail due to tread ply separation. This recommendation is based on testing by Ford and Michelin and is consistent with NHTSA data.
Suburban Tire recommends replacement of tires after they have been in service for 6 years, unless they have been inflated with Nitrogen, consistently maintained over their lifetime with monthly air pressure checks, and the vehicle is garage kept. In this case the recommended service life can be expanded to 8 years if the tread rubber is still supple and the tread depth is over 4/32nds.
Suburban Tire will not perform puncture repairs on tires over 6 years old, or on tires with less than 4/32nds of an inch of tread, due to the increasing likelihood of tread ply separation as a tire gets older and wears out.
These same standards apply to spare tires even if they have never been used, as they are just as prone to failure as tires placed in service on the road. This is due to the higher heat they are exposed to from the road, the muffler, and the warmth trapped in the trunk. The heat bakes the tire and reduces the bonding action between tire components.