At what level of wear should car tires be replaced?

[DiNatalie]

Here are four situations when car tires need to be replaced: 1. Severe tread wear - Generally, there are wear indicators in the middle of the tread. The thickness of the wear indicator is 2mm. If the tire's thickness wears to within 4mm of the limit mark (i.e., 6mm from the deepest part of the groove), the tire should be replaced. 2. Excessive tire repairs - Besides wear, punctures from sharp objects are also a major factor affecting tire lifespan. If the repair is done properly, one or two repairs may not significantly impact driving. However, if the number of repairs exceeds three, caution is needed because no matter how tightly the tire is repaired, gaps will always form between the repair material and the original tire. This can lead to air leakage or blowouts under high-speed or high-temperature driving conditions. 3. Rubber aging - Rubber materials are prone to aging under external factors like light, heat, and moisture, gradually cracking, hardening, and becoming brittle until they lose their usability entirely. Therefore, even if a car is left unused for a long time, tires may still need replacement. If the storage environment is harsh, tires can deteriorate over time. 4. Blowouts, bulges, or sidewall cracks also require tire replacement.