Department of Transportation tire codes indicate vital information about a tire, including its place and time of manufacture and the type and size of the tire. DOT codes are vital for determining the age of a tire when making a purchase or determining if it is potentially affected by recalls.
Tires degrade over time due to breakdown of the compounds in the tire's tread and interior. Many car manufacturers recommend replacing tires after they are six years old, regardless of the amount of wear on the tire. Checking a tire's DOT code is important to avoid buying tires that have aged significantly, as it is not uncommon for tires to sit in warehouses for an extended period before purchase.