Run-flat tyres are built to keep a car moving for a limited distance after a puncture or loss of pressure, rather than leaving the driver stranded at the roadside. They do this with reinforced sidewalls strong enough to support the car's weight even with no air in the tyre. The catch for buyers is that every brand marks them differently.
How run-flats work, and their limits
A conventional tyre collapses once it loses air, because the sidewall cannot hold the weight on its own. A run-flat has a much stronger, self-supporting sidewall that keeps its shape when deflated, allowing the car to be driven on to a safe place or a garage.
That ability is strictly limited. As a general rule, a run-flat can be driven for up to around 50 miles at a maximum of about 50mph after losing pressure, though the precise figures vary by manufacturer and are set out in the car's handbook. Pushing beyond those limits risks further damage and a more serious failure.
Two other points follow from the design. Because a run-flat does not visibly go down when punctured, a car fitted with them relies on a tyre pressure monitoring system (TPMS) to warn the driver. And once a run-flat has been driven on while flat, it generally cannot be repaired, most makers require replacement, and many UK fitters will not repair them at all.
The brand markings
There is no single run-flat marking; each manufacturer uses its own code. The common ones are:
| Marking | Brand(s) |
|---|---|
| SSR | Continental, Uniroyal |
| ROF | Goodyear, Dunlop, Bridgestone |
| EMT | Goodyear |
| ZP / ZPS | Michelin, Yokohama |
| RFT | Bridgestone |
| RSC | Pirelli, and BMW fitment |
| HRS | Hankook |
| MOE | Mercedes-Benz fitment |
| RUN FLAT | Pirelli and others, in plain text |
Two of these double as car-maker fitment marks, RSC on BMW cars and MOE on Mercedes-Benz, which sit alongside the wider set of manufacturer approval markings. Some tyres also show the letter F before the wheel diameter, for example 205/55 RF 16, under the European regulation covering self-supporting tyres. The simplest confirmation, though, is to read the full tyre name and check it against the car's door placard, which states whether run-flats were the original fitment.
Replacing run-flats
A car supplied with run-flats was usually designed around them, firmer suspension tuning to suit the stiffer tyres, and often no spare wheel, since the run-flat is the get-you-home provision. Replacing like-for-like with run-flats keeps that intact, and a matching run-flat is easy to find by size at an online tyre store such as Tyres.co.uk.
Switching to standard tyres is sometimes possible, but it means giving up the run-flat safety feature and being left without a spare unless one is added. Mixing run-flats and standard tyres on the same car is best avoided, as the different sidewall behaviour can affect handling. The ride from run-flats is also firmer than from standard tyres, a trade-off for the reinforced construction.
From the workshop: the question we get most is why a run-flat cannot just be plugged like a normal tyre. The honest answer is that once it has been run flat we cannot see what the sidewall has been through, so replacing it is the safe call, not an upsell.
Sources and accuracy. The run-flat brand codes and the typical 50 miles at 50mph guidance here reflect current manufacturer practice at the time of writing, and brands occasionally update their codes and ranges. The definitive limit for a specific car is in its handbook. If anything here looks wrong, get in touch and we will check it and put it right.
Common questions
How do I know if my tyres are run-flat?+
Look on the sidewall for a run-flat code, which varies by brand: SSR (Continental), ROF or EMT (Goodyear, Dunlop), ZP or ZPS (Michelin, Yokohama), RFT (Bridgestone), RSC (Pirelli, BMW) or simply the words RUN FLAT. The car's door placard and handbook will also state if run-flats are fitted.
How far can you drive on a run-flat after a puncture?+
Typically up to about 50 miles at a maximum of around 50mph, though the exact figure varies by manufacturer and should be confirmed in the handbook. Beyond that, the tyre can suffer further damage and must be replaced.
Can run-flat tyres be repaired?+
Generally no. Most tyre makers advise replacing rather than repairing a run-flat that has been driven on flat, because the internal damage from running deflated cannot be reliably assessed. Many UK fitters will not repair them for this reason.
Can I replace run-flats with normal tyres?+
It is sometimes possible, but it means losing the run-flat safety feature, and a car designed around run-flats often has no spare wheel. Mixing run-flat and standard tyres is best avoided as it can affect handling. The handbook should be checked first.