Run flat tires are tires on which you can continue driving after a puncture, so you can reach an auto shop or safely pull over to change your tire; there’s no need to stop immediately on the roadside.
You shouldn’t drive on them endlessly, though. Always check your manufacturer’s specifications for maximum distance and speed. Run-flat tires let you keep driving after a loss of inflation pressure for up to 50 miles (80 km) at speeds up to 50 mph (80 km/h).
What Are Run-Flat Tires?
Run-flat tires are built to keep a vehicle controllable for a short distance after losing air pressure. This temporary mobility helps drivers move to a safe location instead of stopping immediately on the roadside.
These tires rely on reinforced sidewalls that help support vehicle load during pressure loss, allowing the tire to retain enough shape and stability for limited travel.
Run-flat tires use strengthened sidewall construction and specialized rubber compounds to limit excessive flexing when air pressure drops. This engineering helps the tire stay seated on the rim and maintain usable handling
Because the added structure can make pressure loss harder to detect, vehicles equipped with run-flat tires need a Tire Pressure Monitoring System, or TPMS, to provide timely alerts when inflation decreases.
How Do Run-Flat Tires Work?
Run-flat tires come in two primary types: the self-supporting system and the support ring system.
In self-supporting run-flat systems, the tire has reinforced sidewall construction that enables the tire to support the vehicle even after air loss. This design allows continued use after the air becomes depressurized up to the manufacturer’s specified speed and distance.
In support ring run-flat tire systems, a ring of hard rubber or other such structure is used to support the weight of the vehicle in the case of an air loss.
Since most run-flat tires will still perform when “flat,” all run-flat tires must to be placed on a vehicle equipped with a Tire Pressure Monitoring System (TPMS). The tire pressure monitoring system will tell you immediately if one of your tires loses pressure. Without the TPMS, you’d have no way of knowing you were driving with an underinflated tire.
If you do have a flat tire, there is no consensus on whether or not run-flat tires should be repaired. Tire manufacturers typically warn consumers to look to the vehicle manufacturer’s replacement tire recommendations and restrictions.
For instance, Michelin North America Inc. deems it acceptable to repair its run-flat tires (Zero Pressure) under some guidelines. However, the owner’s manual for BMW states that you cannot repair their original equipment run-flat tires.
Types of Run-Flat Tires
Run-flat tires feature one of two basic layouts that can keep the wheel itself well away from the ground in the event of a typical puncture or other air loss.
Supporting Ring System
Less common is a supporting ring system. These tires employ a central ring of hardened rubber to support the vehicle in air-loss situations. Few mass-market vehicles include them, though certain heavy-duty or military-oriented cars may come with this tire type.
Self-Supporting Sidewall System
The most common is a self-supporting sidewall, which features reinforced construction of hard rubber that won’t collapse after a tire puncture. A variety of manufacturers make self-supporting run-flat tires.
Their sidewalls can be several times beefier. While you can drive on them for short distances thanks to those thick sidewalls, they are not true “airless” tires. Such designs have been tested but not yet offered on regular-production vehicles.
Advantages
- Convenience: Run-flat tires are all about convenience. While today’s tires are far less susceptible to punctures and other air-loss situations than those in years past, all it takes is a strip of metal or a long nail to ruin your day.
- Safety: With these specialized tires, you may be able to continue to your destination or at least to a shop that can remove and replace the punctured tire. A driver needs to pull over immediately — perhaps even onto the side of a busy highway — if they have a conventional flat tire.
- Rides well when flat: Because they maintain the primary “carcass,” or shape, of the tire, they mean relatively little handling and ride compromise after a puncture. A conventional tire will handle much differently — especially when punctured and the tread rubs against the metal of your wheel.
- No spare tire: A vehicle built with run-flat tires when it was new won’t have a spare tire, reducing weight and increasing cargo space.
Drawbacks
- High replacement cost: Drivers often think about the cost of replacement as one of the most significant downsides to run-flat tires. But the thick sidewalls that make them so good at their job have a significant impact on ride quality.
- Stiffer ride: Run-flats ride stiffly, which may displease drivers looking for a plush cruise. Their unique tread patterns can also lead to shorter tire life and more necessary repairs.
- Not 100% indestructible: Impact with a large or especially vicious piece of shrapnel may cause enough damage to render a run-flat unsafe to drive on, the same way a destructive event impacts a standard tire. And if that happens, the lack of a spare tire in a run-flat-equipped car means you’ll be calling a tow truck.
- Not easy to replace: Replacing these wheels isn’t relatively as easy, either. Tire shops do not always stock them. So, drivers in smaller towns or rural areas may need to wait days for a replacement to arrive from a warehouse.
Run-flat Tire Costs
Run-flat tires typically cost between $150 and $500+ per tire, generally running 35% to 200% more than conventional tires due to reinforced sidewalls. They are often harder to repair, frequently requiring full replacement, and usually need to be replaced in pairs or sets.
Considering they usually should be replaced in pairs, expect to pay from $300 to 1,000 per set. If you need to replace all four tires, the total cost may range from $600 to 2,000 to replace with run-flat tires, which does not include installation and alignment.
How long do run-flat tires last?
Run-flat tires generally last between 30,000 and 50,000 miles, with some performance models wearing out as early as 15,000–20,000 miles. While they offer a similar lifespan to conventional tires, their stiffer sidewalls can lead to faster tread wear. After a puncture, they typically last for about 50 miles at speeds up to 50 mph.
Are run-flats worth it?
To see if a run-flat tire will be worth it or not, there are a few factors you should analyze first. For example, do you frequently drive on poor-quality pavement with a high likelihood of a puncture event?
If so, then it could be worth the price of admission as it prevents you from being stranded with a flat tire. Generally speaking, a run-flat tire will not strand you on the side of the road, in most cases. They work, but they are not perfect – yet.
How fast can you drive on run-flat tires?
Most run-flat tire manufacturers suggest you should not exceed 55 mph, but sometimes, one tire manufacturer may have different recommendations.
Therefore, it’s best to refer to the documentation from the manufacturer you purchased the run-flat tires from originally. Once the run-flat tire is driven over the manufacturer-recommended limit, it may not be safe to drive on it ever.
Are run-flat tires noisy?
Because the side walls on run-flat tires are thicker than those of a conventional tire, there will be slightly louder road noise. You may also feel that your car has a bigger bump than would be felt on a rough or uneven road, but test drive a car with run-flat tires before deciding!