How deep is the allowable scratch on the sidewall of a tire?
3 Answers
Tire sidewall scratches exceeding 4mm require immediate replacement. This is because the rubber thickness on tire sidewalls typically does not exceed 1cm. Any damage to this area has a high probability of reaching the radial ply layer. Once the radial ply is compromised, the structural integrity of the entire tire cannot be guaranteed, posing an imminent risk of blowout. Relevant information follows: Important Note: Any visible scratch necessitates replacement as it indicates damage to the internal cord fabric material. Continued use carries blowout risks and jeopardizes driving safety. Tire Definition: Tires are circular elastic rubber products assembled on various vehicles or machinery for ground contact and rolling. Mounted on metal rims, they support the vehicle body, absorb external impacts, maintain road contact, and ensure driving performance.
This is absolutely no joking matter! Last time, I personally witnessed a friend's car tire with a sidewall scratch—just a tiny mark—and the repair shop mechanic immediately advised him to replace the tire. The sidewall of a tire is only about 5 millimeters thick, but its internal structure, like the cord ply and air barrier layer, is extremely delicate. A scratch deeper than 2 millimeters is very dangerous, especially if it damages the internal nylon cords, which are essentially the tire's skeleton. At high speeds, with increased tire pressure, it could bulge or blow out at any moment. Here's a simple way to check: apply soapy water to the scratch, and if you see bubbles after inflating, the tire is definitely unusable. Don't hesitate over a thousand bucks—your life is worth far more than a tire!
The sidewall of a tire is like the arterial vessels in the human body, with a thin layer of rubber covering the supporting layers beneath. The most extreme case I've seen was a cut just 1.5mm deep, which tore open a 10cm gash when driving at high speeds. While there's no fixed safety standard, experienced mechanics will tell you: replace the tire immediately if you see the cord layers, and replace it if the cut is longer than 3cm no matter how shallow it is. By the way, sidewall repairs are just nonsense—they can't withstand the twisting forces when the tire turns. Avoid scraping against curbs when parking, and always check the manufacturing date when replacing tires—older tires over five years are more prone to cracking.
