Every tire sold in the United States carries a DOT (Department of Transportation) identification number on its sidewall. This alphanumeric code contains valuable information about your tire, most critically its manufacturing date. Understanding how to read this code helps you verify tire age, which is an important safety factor that many drivers overlook.
The DOT code is located on the lower sidewall of the tire and begins with the letters "DOT" followed by a series of characters. The full code may be on only one side of the tire, so if you see "DOT" followed by just a few characters on one side, check the other side for the complete code. The first two characters after "DOT" identify the manufacturing plant. The next two characters are the tire size code. Additional characters in the middle identify brand-specific characteristics. The most important part is the last four digits, which reveal the tire's manufacture date.
The final four digits represent the week and year of manufacture. The first two digits indicate the week (01 through 52), and the last two indicate the year. For example, a code ending in 2524 means the tire was manufactured in the 25th week of 2024, which corresponds to late June 2024. A code ending in 0323 indicates the 3rd week of 2023, or mid-January 2023. This dating system has been standard since 2000. Tires manufactured before 2000 used a three-digit date code, but any tire that old should have been replaced long ago regardless.
Why does tire age matter? Rubber compounds degrade over time through a process called oxidation, even on tires that have never been used. The rubber hardens, becomes less flexible, and loses its ability to grip the road effectively. Internal adhesive bonds weaken, increasing the risk of tread separation. Most tire manufacturers and automotive safety organizations recommend replacing tires that are six to ten years old regardless of remaining tread depth. Some manufacturers specify a maximum age of six years, while others allow up to ten years with regular inspections. Heat, UV exposure, and storage conditions can accelerate aging.
When purchasing tires, DOT codes let you verify you're receiving fresh inventory. Ideally, you want tires manufactured within the last 12 to 18 months. Reputable retailers like Ship.Tires maintain fresh inventory with regular stock rotation. If you receive tires that are more than two years old, you have legitimate grounds to request newer stock. Also check the DOT codes on your current tires periodically, especially on vehicles that aren't driven frequently like RVs, trailers, and classic cars. These vehicles often have tires that age out before they wear out, creating a hidden safety risk that's easily caught by a quick sidewall check.