The Number On Your Tires You Need To Check (And What It Means)

The tires in your car are consumable and require periodic replacement. Balding tires or those with worn-out treads are dangerous and not deliver the same levels of traction and braking as newer rubber. However, tire age is more important regardless of the tread depth. Tires undergo thermo-oxidative degradation as they age, and it causes the rubber compound to crack or dry after repeated exposure to sun, wind, and rain.

According to an NHTSA consumer advisory in 2008, the agency reported 159 vehicular crashes caused by tire failure or tread separation, and all the cars involved had old tires that were more than six years old. The crashes resulted in 128 deaths and 168 injuries. The NHTSA began examining tire aging after the infamous Ford/Firestone safety nightmare in 2000.

Moreover, an NHTSA report states that tire aging occurs regardless of the miles driven, and older tires are more susceptible to failure or blowouts. That's why checking the age of your tires is just as important as the tread depth and inflation pressure.

The sidewall of your car's tires has a litany of numbers and letters that describe the brand, make/model, size, load rating, speed symbol, and other vital aspects of a particular tire. Most noteworthy is the DOT Tire Identification Number (TIN), which contains information like codes for the tire plant, manufacturer, and tire size codes. The TIN could easily be found by locating the DOT marking. 

However, the last four numbers after the PIN indicate the week and year of manufacturing, which also shows the tire age. The sample image above shows that the "1822" marking represents the 18th week of 2022. For example, if your tire's TIN ends with 4921, the tire was manufactured in December 2021. If you still have that tire on your car, the tire is roughly two years old.

The NHTSA recommends replacing tires over five to six years old, regardless of the tread wear or tire condition. Remember that tires are the only things keeping your car on the road, and you should absolutely follow the expert's tips when buying new car tires when people's lives are on the line.