What does DOT on tires mean?
3 Answers
Tire DOT stands for the certification by the U.S. Department of Transportation. It is usually followed by a series of numbers and letters, which represent the tire's origin information and factory code. The last four digits indicate the tire's production date, with the first two digits representing the production week and the last two digits representing the production year. Tires are a crucial component of a vehicle, with more than ten types of markings on them. Correctly identifying these markings is essential for selecting, using, and maintaining tires, as it plays a significant role in ensuring driving safety and extending tire lifespan. Car tires are in direct contact with the road surface and, together with the vehicle's suspension system, play a vital role in cushioning the impact experienced during driving.
I always check this DOT mark when changing tires. It's actually the certification logo of the U.S. Department of Transportation, and that string of alphanumeric characters following it contains important information. I specifically asked a repair shop technician, and the last four digits are particularly crucial: for example, 3219 means the tire was produced in the 32nd week of 2019. Tire lifespan is directly linked to its production date because rubber naturally ages. Even if the tires haven't been used much, they should be replaced if they're over six years old. Every time I help friends check used cars, I squat down to inspect the tire DOT code. If I find tires produced five years ago still in use, I always advise replacing them immediately. This mark is located on the tire sidewall, and the row starting with the letters DOT is the one to look for.
When researching auto parts, I found the DOT code incredibly useful. Simply put, it's the ID number of a tire, serving as a certification mark approved by the U.S. Department of Transportation for safety. Once while helping a neighbor change tires, I noticed the last four digits of the code were 2322, immediately recognizing it meant the tire was produced in the 23rd week of 2022. The repair manual states that the production date of a tire directly impacts safety—even brand-new tires stored for over three years should be used with caution. This is especially true in high-temperature regions like the South, where rubber degrades faster. Now when selecting tires, I always check the last four digits of the DOT code to avoid older stock. This knowledge is also mentioned in the "Motor Vehicle Safety Technical Specifications."
