Can Run-Flat Tires Be Repaired After a Blowout?
3 Answers
Run-flat tires can be repaired after a blowout, but there are certain situations where repair is not recommended, and replacement is advised instead: 1. If the puncture hole is too large, exceeding 4.2 millimeters; 2. If the puncture is located on the tire sidewall; 3. If the tire was punctured and lost air, causing damage while driving; 4. If the tire has already been repaired twice and cannot be repaired again. Methods for repairing run-flat tires include using rubber plugs, mushroom plugs, and automatic tire repair fluids. The mushroom plug repair method involves a mushroom-shaped rubber patch. The repair process involves locating the puncture from inside the tire, threading the mushroom stem through the hole, trimming the excess stem on the outside, and securing the inner part with special adhesive. The stem part provides an external repair effect, while the inner part acts as an internal repair. Run-flat tires are technically known as "self-supporting tires" and consist of an outer tire, a standard inner tube, a spare inner tube, a steel rim, a gas generator, a pressure sensor, and a control unit.
Yesterday, I had a nail puncture in my run-flat tire and rushed to the repair shop. The mechanic said it depends on the location and size of the damage. A small hole like mine in the center of the tread can be fixed with a mushroom plug, and the tire can still be used normally after repair. However, if the damage is on the sidewall or exceeds 6mm in diameter, it can't be repaired and must be replaced. The repair cost me 50 yuan, while a new tire would have been over 1,200 yuan—luckily, it was repairable. I regularly check my tires since run-flat tires only allow you to drive up to 80km with a puncture, not that they never fail. It's been half a month since the repair, and the tire has been stable even on highways. The key is to have a professional assess the damage.
Last time I specifically consulted a tire engineer, and learned that run-flat tires have a special structure with a reinforced sidewall support layer. If only the tread is punctured by a nail, it can be safely repaired without affecting safety. However, if the damage is on the sidewall where deformation and pressure are high, repairs are prone to re-cracking. For patching, hot vulcanizing rubber or mushroom plugs must be used, as ordinary rubber strips can't withstand high-speed friction. Performing wheel balancing after repair is crucial to avoid vibrations. It's generally recommended not to exceed 120 km/h after patching and to regularly check the repaired area for air leaks. After all, safety comes first—don't hesitate to replace the tire if necessary.
