Beside the black stripes surrounding the windshield, on newly produced cars or cars that have just changed tires, there are often yellow and red circles on the tire walls and rims. Most people don’t pay attention to this small detail, but according to car experts, it is the intention of the manufacturer.
In fact, the yellow and red circles on the car tires are to ensure the balance of the rims and tires during operation.
Circular mark on car tires. (Photo: Getty)
The tire material is made of rubber, synthetic fiber, steel fiber, and chemicals to resist corrosion and heat. Although the manufacturer has applied many technologies to optimize, each tire cannot avoid a certain margin of error that cannot be identified with the naked eye. Therefore, after production, the tires are tested and measured with specialized machines to determine the lightest position on the tires and mark a yellow circle right at that position.
Additionally, the heaviest point of the rim, where the valve head is fixed to inflate air into the tire, is also marked yellow. Rim manufacturers said that when fitting the tire onto the rim, the installation must align the marking on the tire with the fixed position of the valve head on the rim to ensure the balance of the rim and tire.
After a period of use, the yellow circles marking on the tire walls will gradually fade away. When that happens, technicians often use specialized machines and equipment to check. If they detect any imbalance, they will attach counterweights (lead sheets) to the rim.
The produced tires are not only uneven in weight but they also cannot be perfectly round. Manufacturers test the most eccentric point of the tire and mark it with a red circle. This is called the high point (Hight Pot) of the tire.
Similarly, on the rim, there will be a point marked in red called the low spot – the closest point to the center of the rim. The difference between the high point and the low point is called the radial runout.
In the assembly process, to eliminate radial runout on the rim and tire, the manufacturer usually aligns the high point on the tire with the low point on the rim (i.e. two red circles on the rim, the tire aligned).
Nowadays, advanced technology helps rim manufacturers produce completely round tires, and users rarely see red markings on the rims. However, yellow circles sometimes still appear on common car models.
According to VTV.vn
