Can a run-flat tire be replaced individually?
4 Answers
Can a run-flat tire be replaced individually? Introduction to run-flat tires: Run-flat tires are technically known as "Self-Supporting Run-flat Tires", abbreviated as RSC. The inflated sidewall of the tire is the main part that supports the weight of the vehicle, especially for tires with a larger aspect ratio (the ratio of tire height to width), where the sidewall is very thick. Precautions for using run-flat tires: There is a phenomenon called "standing waves" in car tires, which often occurs when driving at excessive speeds. This phenomenon can rapidly increase tire temperature, accelerate rubber aging, and easily cause delamination and rupture, leading to tire blowouts. To ensure even wear across all tires and extend their service life, it is necessary to regularly rotate the tires as specified, usually during secondary maintenance. Vehicles frequently driven on highways should adopt the rotation method.
Just heard the mechanic talking about this at the repair shop. Run-flat tires really can't be replaced just one at a time for convenience. My car had a nail puncture last time, and we did just that, resulting in severe pulling to one side. The key issue is these tires have extremely stiff sidewalls—even a difference of just a few thousand kilometers between old and new tires can create a diameter difference of several millimeters. The car's computer-controlled braking system gets confused, especially when turning in the rain, causing the ABS to rattle like crazy. The mechanic said you need to replace at least two tires together, and for all-wheel-drive vehicles, it's better to replace the whole set, otherwise the differential could get wrecked. His advice was to temporarily move the punctured tire to the rear axle, then quickly find a matching tire of the same model to pair it with—preferably installing the new tires on the drive wheels.
For those who frequently drive long distances, it's advisable not to skimp on this expense. Run-flat tires wear more noticeably than regular tires, and even if the other tire has only run 10,000 kilometers, the degree of rubber aging differs. Once, I only replaced the front right tire on the highway, and the steering wheel kept pulling to the left. More importantly, it affects safety: different grip levels on both sides can easily cause the car to fishtail during emergency braking. Nowadays, tire shops have machines to measure the diameter difference between tires; if it exceeds 3%, you can't replace just one. If it's a temporary emergency, you can mount the new tire on the rear axle for a few days as a transition, but for long-term use, you'll have to grit your teeth and replace two. Some cars can turn off the vehicle stability system, but the fault light will stay on.
It depends! If the tire is less than 2 years old, the wear marks are within the safety limit, and you can find an exact same model from the same production cycle, theoretically you can replace just one tire. But the technician at the 4S shop told me that run-flat tires produced last year can have 10% less grip compared to this year's. Especially for rear-wheel-drive cars, you need to be extra careful since the drive axle bears significant force. When I only replaced the left rear tire on my BMW, I always felt the rear end sliding during rainy cornering. In the end, I spent 600 bucks on a four-wheel alignment to fix it, which was more expensive than buying a single tire. Nowadays, online tire shops offer discounts for pairs, so it's more cost-effective to keep the old tires as spares when buying new ones.
