Run-flat tyres (RFTs) are a specialist type of tyre designed to stay secure even when tyre pressure is at zero, allowing the motorist to keep driving rather than stopping to change a tyre.

The benefits of run-flat tyres include:

Reduced weight of vehicle. Run-flat tyres work out lighter than standard wheels and tyres, which would also require a spare, jack and wheel brace. A vehicle that weighs less means better fuel efficiency.
Fewer materials are required to manufacture an RFT, making them more environmentally friendly.
There is no need for a spare tyre, meaning more space in the boot and a lighter load.
There is no great difference in performance and ride if a run-flat tyre suffers a puncture, providing you with safe handling and cornering and reducing the risk of an accident.
These systems were primarily created to keep drivers safe, as punctures and blowouts can be dangerous, and account for a large majority of fatal accidents on the road. Aside from safety, a flat tyre can be a real inconvenience, adding time and cost to your journey. Changing a tyre is fairly straightforward, but it often occurs at the most inopportune moment - getting stuck on the side of a motorway or in the pouring rain with hungry, tired, noisy kids in the backseat is no fun at all! And trying to change a tyre on the hard shoulder can be dangerous in itself, or even impossible if you are disabled or elderly.

Many different manufacturers have developed their own RFT ranges, and they can differ slightly in the way they are constructed, but the fundamentals are the same, ensuring that the tyre beads remain securely attached to the rim of the wheel, no matter whether pressure has dropped.

Tyre failure can be very serious, especially at higher speeds. A puncture or blowout can cause loss of control, much increased braking distance and reduced grip. When this occurs, the sidewall separates from the rim flange due to the drop in internal pressure, and drops into the inner wheel. This can cause loss of control, and, potentially, an accident.

Run-flat tyres reduce this risk by keeping the tyre beads anchored to the rim flange, even when air inflation (which is what keeps normal tyres in place) goes down to zero pressure. Therefore your tyre continues to perform safely, meaning you don't need to stop and change your tyre, or risk a frightening loss of control.

Vehicles that come with RFTs are usually not equipped with a spare tyre, and it is not recommended to repair a run-flat tyre, as they are put under a huge amount of pressure and stress and there may be internal damage that is not visible. This is because an RFT carries the weight of the car on the extra-strengthened sidewall, as opposed to a pneumatic tyre which carries the weight using the pneumatic effect of the air inside.

Michelin, Goodyear, Dunlop, Bridgestone, Pirelli and Continental all manufacture RFTs, and BMW is the largest user of run-flat tyres as Original Equipment (O/E), ie: providing run-flat Shock obserber Replace Harlow as standard. Audi, Chrysler and Ferrari also offer run-flat tyres as O/E on some models.

Any vehicle equipped with run-flat tyres should also include a Tyre Pressure Monitoring System (TPMS) to determine whether pressure has been lost, as it may not be discernible by the difference in ride.Run-flat tyres are meant to maintain speed, handling and smoothness of driving when a puncture occurs, even on a motorway. A TPMS is essential to alert the driver to a loss in tyre pressure, otherwise the tyre may be overworked in its emergency state and eventually cause it to fail too. TPMS works in two different ways - either by a sensor fixed to the wheel, inside the tyre, or by using the vehicle's ABS.