There are 6 criteria for judging how soon car tires should be replaced. As long as one of the criteria is met, the tires should be replaced.
First, each tire has a drainage groove, and there is a raised square in the drainage groove. The shape of the square may be different for different tires, but this does not affect the observation. As long as the tire pattern has been worn to the level of the raised square, then this tire will not only affect the braking stroke, but also increase the risk of puncture, so it must be replaced at this time.
Second, there are 4 digits on the tire, which is the production date of the tire. The first two digits represent the week number, and the last two digits represent the year. For example, if the number of this tire is 4220, it means it was produced in the 42nd week of 2020. Tires are rubber products and will age. Generally, they need to be replaced every 5-6 years. Therefore, we have to estimate based on the production date of the tire. If we push it back five or six years, even if the tire wear is not severe, it is time to replace the tire. , but there is a process of aging, and these five or six years are not a hard indicator. If you are running at high speeds for a long time, it is recommended to replace them immediately when the time comes. After all, high-speed tire blowouts are quite dangerous. But if your car is only used for commuting in the city all year round, then it doesn't matter if you delay the replacement for a while, but there is a limit, which should not exceed 8 years. Even if it is a new tire that has never been used, It can no longer be used after 8 years.
Third, if the tire has a bulge, it usually means there is a problem with the ply. The risk of tire blowout is very high. Regardless of the pattern wear and how long it has been used, it should be replaced immediately. If the bulge appears on the inside of the tire, it will not be visible if you are not careful. If the summer comes, it is the season when tire blowouts are most common. Be sure to check the tires regularly to see if there is any bulge.
Fourth, if the side of the tire is punctured, there is no point in repairing the tire. In this case, the only option is to replace the tire.
Fifth, if the diameter of the punctured tread exceeds 6 mm, there is no need to repair the tire. It is recommended to replace it directly.
Sixth, different brands have different requirements for the number of tire repairs. Some brands only allow tire repairs once, while others allow you to repair tires 4 times. There are also requirements for the place where the tires should be patched each time. For example, Bridgestone. The required distance is greater than 40 centimeters. If it is not met, the tire cannot be repaired. Michelin requires the central angle to be greater than 90 degrees. What does it mean? It means that the tire is divided into four equal areas, and there cannot be two tire repair points in one area. Of course, the manufacturer's requirements must be relatively strict, and we don't pay much attention to it on weekdays. However, if a tire has been repaired more than 4 times, stop repairing it and replace it.
