How many centimeters can a tire be punctured before it leaks?
3 Answers
If a car tire is punctured more than 13mm (7mm tread depth and 6mm crown thickness) on the tread, it will leak. If the sidewall is punctured more than 5mm, it will also leak. Methods to determine if a car tire is leaking: If a puncture is found during inspection, first locate the puncture site, then immediately spray soapy water on it (plain water can also be used). If bubbles appear after application, it indicates the tire is indeed leaking. If bubbles form rapidly, it means the tire is leaking severely and should be repaired at a service shop immediately. How to handle a punctured car tire: When a tire is punctured, never pull out the nail directly, as this may cause severe leakage and make the tire unusable. Most car tires on the market today are tubeless tires, which leak slowly when punctured by a nail, allowing sufficient time to drive the car to a repair shop.
Whether a tire leaks after being punctured mainly depends on whether the inner layer is penetrated. Generally, a nail a few millimeters long can cause a tire to leak, let alone something several centimeters long. The rubber layer of the tire tread is only about 1 cm thick, so objects like screws that are 3-5 cm long will definitely pierce right through. I once met a fellow driver whose tire was punctured by a 5 cm steel bar, and the air leaked out faster than blowing up a balloon. The key factor is the location of the puncture—if it's on the tread, it can still be repaired, but if the sidewall is punctured by several centimeters, the entire tire is basically ruined. In such cases, it's best not to drive on it; instead, change to the spare tire or call for roadside assistance immediately, or else the wheel rim could also get damaged.
If a tire is truly punctured by an object several centimeters long, it will definitely leak air. You should know that the inner sealing layer of a tire is extremely thin—even a tiny needle hole can cause air to slowly escape. I’ve changed tires myself and found that beneath the tread rubber layer lies the steel-belted ply, with the innermost air-retention rubber layer being the most critical. If a sharp object several centimeters long penetrates and damages this layer, it’s game over. Larger punctures leak air much faster, potentially flattening the tire within just a few kilometers of driving. Once, I saw someone with a 10-centimeter-long metal shard stuck in their tire, and the car wobbled like it was limping. That’s why if you discover a puncture, never pull out the foreign object—head straight to a repair shop for a safe fix.
