- How do run-flat tyres work?
- Are they necessary?
- Parkers explains the tech
Run-flat tyres are specifically designed to survive being driven on for a short time after experiencing a puncture.
The name “run-flat” comes from their ability to operate effectively when deflated, without quickly disintegrating as a standard tyre could.
How do run-flat tyres work?
They have a strengthened internal structure and tougher sidewalls which enable the tyre to maintain its shape better should a puncture occur. Because of this, the risk of an accident following a tyre blowout – where a tyre bursts while driving – is also reduced.
All run-flat tyres will have a maximum rating of both the speed and distance they can cover after a puncture. These vary depending on the driving conditions and vehicle.
That said, manufacturers claim that road-holding is only marginally affected when the tyres are deflated. Another benefit is the level of space- and weight-saving in the boot, as a spare wheel is no longer necessary.
Due to the tougher construction, though, run-flat tyres are likely to weigh more than conventional alernatives.
Do I need them?
Tyres which keep their structure even after losing pressure can be incredibly useful, and possibly life-saving, should you suffer from a puncture on a motorway or in poor driving conditions.
Instead of having to pull over onto the – highly dangerous – hard shoulder and waiting for assistance, run-flats should allow you to keep moving until your destination – or the nearest garage.
A potential downside of run-flats, however, is that they can make the ride firmer – due to their reinforced construction – and affect roadholding, with different levels of grip to standard tyres. Because of this, we would recommend you test drive the car first to decide whether you're happy with the tyres.
Run-flat tyres can also cost more than ordinary equivalents. Also bear in mind that it is unwise to fit them to cars that were not available with them as standard.
Take note too that due to their unique design reinforced tyres are seldom repairable and must be scrapped should they suffer from any form of pressure loss that can't be addressed by simply topping up the tyre pressure.
Available on a number of modern vehicles, reinforced tyres are sometimes offered standard or as a cost-option on cars such as the BMW 1 Series and MINI Hatch.
They can be retrofitted in place of standard tyres, though it’s best to consult the vehicle manufacturer if you’re thinking about making the switch, to make sure the car handling will not be adversely affected.
Tyre pressure monitoring system, self-sealing tyres