1：What is it used for?
After the tire loses air pressure, you can continue driving for a certain distance to reach a repair point to fix or replace the tire.
2：Did you know?
This feature is also commonly known as "run-flat tires." Although they are called run-flat tires, they cannot actually prevent tire bursts. They only prevent the tire from instantly losing its support and causing severe tilting when a blowout occurs. However, some military special vehicles or presidential vehicles do have tires that can truly resist explosions and bullets.
When driving with zero tire pressure, make sure not to drive too fast and immediately find a repair point nearby. Generally, the speed is limited to 80 km/h, and you can continue driving for 80 km.
Run-flat tires are relatively hard because they have reinforced sidewalls to prevent blowouts, which may affect the comfort to some extent.
Repairing a punctured run-flat tire can be quite troublesome. Due to the thick and hard sidewalls, it is not easy to remove the tire. Even with the use of machines, it can be challenging, and improper operation may cause irreparable damage to the sidewalls. Therefore, you either need to directly replace the tire (which is relatively expensive) or go to a professional repair shop for repairs.
Although run-flat tires have a relatively long lifespan, they should be replaced after four years or when the wear indicator reaches the limit because rubber deteriorates over time.
Vehicles equipped with this feature generally do not have a spare tire but have a tire pressure monitoring system. The weight of four run-flat tires is comparable to that of five regular tires.
Due to the high cost, run-flat tires are not widely equipped by the original manufacturers. If you need them, you can purchase and replace them later.
3：Technical Principle
The "continue driving with zero tire pressure" feature is actually the function of "run-flat tires." Run-flat tires are also known as "self-supporting tires." The English abbreviation for this is RSC (Run Stability Control).
Run-flat tires have strong sidewall support and resilience even when they have no air pressure, while regular tires would be severely compressed by the wheel hub and collapse.
4：Further Reading
Products from various tire manufacturers:
Currently, there are quite a few brands and specifications of run-flat tires available in the market for passenger cars. Brands like Michelin, Bridgestone, and Continental have their own run-flat tire products.
ZP tires are Michelin's "zero pressure" tires (ZP stands for zero pressure). Michelin ZP tires are not a specific tread pattern but must be combined with the product's tread pattern name. For example, Pilot Pirmacy ZP, Pilot Sport PS2 ZP, Latitude Tour HP ZP (for SUV models).
Bridgestone's run-flat tires are identified by the label RFT (Run Flat Tire). The newer RFT tires from Bridgestone have improved the issue of harder sidewalls in traditional RFT tires, enhancing comfort. Examples include RE050A/RFT for the sports series and ER300/RFT for the comfort series.
Continental's run-flat tires are labeled SSR (Self Supporting Run-flat) and are known as advanced tires with loss of pressure endurance for safe driving. Examples include ContiPremiumContact SSR and ContiSportContact 2/3 SSR.
It is important to note that run-flat tires are not available in all tire models; they are mainly produced for mainstream and large tire sizes.
