Why New Tires Have Colored Stripes on the Tread

If you have bought new tires, you may have seen bright colored lines painted around the tread. Carscoops explains that they help factories identify products and rubber mixes as tires move through production. They are meant for the people and machines making the tires, not for the person who buys them.

A German company called REA, which supplies marking equipment to the tire industry, says its automated color lines are used to identify the type of material. The systems can mark rubber parts and finished tires, so workers or machines can tell one kind from another. By the time the tires reach a store and are put on a car, the lines have done their job, and they wear off as the tires collect miles.

The colors have no universal meaning. The tire industry has not agreed on one system, so a blue line on one brand's tire does not mean the same as a blue line on another brand's. The markings belong to each maker's own identification system. Two colors can also work together to identify a tread mix, so reading just one stripe would miss part of the message. Treating every red stripe as a certain performance rating would be a poor shortcut.

What should buyers look at instead? A tire's size, model, load index and speed rating are printed on the sidewall, and some information is coded. For example, a date code such as "2125" means the tire was made in the 21st week of 2025. That matters because most tire makers recommend replacing tires every five or six years even if there is tread left, and the code lets you check that you are not buying tires a year or two older than brand new.

Directional tires also have an arrow on the sidewall showing which way they should rotate, and a fitter must follow it. That is an installation instruction, unlike the colored stripe, which is only for the factory.