What are the yellow and red dots on car tires for?
When buying a new car, owners often notice yellow and red dots on the tires. Are these just for decoration, or do they serve a special function?
Besides the black dots surrounding the windshield, new cars or cars with recently replaced tires often have yellow or red dots on the tire sidewalls and rims. Most people don't notice this small detail, but according to automotive experts, it's intentional on the part of the manufacturer.
In fact, the yellow and red dots on the tires are there to ensure the balance of the rim and tire during operation.
Tires are made from materials such as rubber, synthetic fibers, steel fibers, and chemicals that provide wear resistance and heat resistance. Although manufacturers apply many technologies to optimize production, each tire inevitably has a certain degree of error that is imperceptible to the naked eye. Therefore, after production, tires are inspected and measured using specialized equipment to determine the lightest point on the tire, and a yellow dot is marked at that location.
Additionally, the heaviest point on the rim, where the valve stem is fixed for inflating the tire, is also marked in yellow. Rim manufacturers state that when mounting a tire, the markings on the tire sidewall must align with the valve stem's mounting position on the rim to ensure proper wheel and tire balance.
After a period of use, the yellow dots marking the sidewall of the tire will gradually fade. At that point, repair technicians usually use specialized machinery and equipment to check for imbalance. They will attach counterweights (lead weights) to the wheel rim if they detect any imbalance.
Tires produced are not only uneven in weight, but they also cannot be perfectly round. Manufacturers check the point furthest from the center of the tire and mark it with a red dot. This is called the tire's high point (High Pot).
Similarly, the wheel rim will also have a red-marked point called the low spot – the point closest to the center of the rim. The difference between this high and low point is called the off-center offset.
During assembly, to eliminate eccentricity on the wheel and tire, manufacturers typically align the high point on the tire with the low point on the rim (i.e., the two red dots on the rim indicate a straight tire alignment).
Nowadays, advanced technology allows tire manufacturers to produce perfectly round tires, and users rarely see red dots on wheel rims. However, yellow dots still occasionally appear on some mainstream vehicles.
