Run-flat tyre guide
What is a run-flat tyre?
A run-flat tyre has reinforced sidewalls that support the vehicle's weight even after a complete loss of air pressure. This allows you to drive to a safe location or tyre shop — typically up to 80 km (50 miles) at a maximum of 80 km/h (50 mph) after a puncture. Most new BMWs, MINIs and some Mercedes models are fitted with run-flats from the factory, meaning they carry no spare wheel. Run-flats are identified by markings such as SSR (BMW), RFT, ZP (Michelin), or ROF (Bridgestone).
- A run-flat tyre has reinforced sidewalls that support the vehicle's weight even after a complete loss of air pressure.
- This allows you to drive to a safe location or tyre shop — typically up to 80 km (50 miles) at a maximum of 80 km/h (50 mph) after a puncture.
- Most new BMWs, MINIs and some Mercedes models are fitted with run-flats from the factory, meaning they carry no spare wheel.
FAQ
- What is a run-flat tyre?
- A run-flat tyre has reinforced sidewalls that support the vehicle's weight even after a complete loss of air pressure. This allows you to drive to a safe location or tyre shop — typically up to 80 km (50 miles) at a maximum of 80 km/h (50 mph) after a puncture. Most new BMWs, MINIs and some Mercedes models are fitted with run-flats from the factory, meaning they carry no spare wheel. Run-flats are identified by markings such as SSR (BMW), RFT, ZP (Michelin), or ROF (Bridgestone).
- What should I verify before using this information?
- Use TireFitLab values as a sizing reference, then verify the vehicle handbook, tire placard, rim compatibility, load rating, and physical clearance before fitting.
How run-flat tyres work
Standard tyres rely entirely on air pressure to carry the vehicle load. When pressure is lost, the sidewall collapses and the tyre is destroyed within seconds of driving.
Run-flat tyres use one of two main technologies:
- Self-supporting (SST) — the most common type. Extra-stiff reinforced rubber inserts in the sidewall carry the load even at 0 PSI. The sidewall is visibly thicker than a standard tyre.
- Support ring (SRT) — a hard ring attached to the wheel rim that the tyre rests on if pressure is lost. Less common; used on some high-performance vehicles.
Key limits: After a pressure loss, run-flats must only be driven at ≤ 80 km/h (50 mph) for a maximum of 80 km (50 miles). Exceeding these limits causes irreparable sidewall damage and is dangerous.
Run-flat markings by brand
| Brand | Code on sidewall | Full name |
|---|---|---|
| BMW / MINI | SSR | Self-Supporting Runflat |
| Michelin | ZP | Zero Pressure |
| Bridgestone | ROF | Run On Flat |
| Goodyear | ROF / EMT | Extended Mobility Technology |
| Continental | SSR | Self Supporting Runflat |
| Pirelli | r-f / RFT | Run Flat Technology |
| Dunlop | DSST | Dunlop Self-Supporting Technology |
Run-flat vs conventional tyres
| Aspect | Run-flat | Conventional |
|---|---|---|
| Spare wheel | Not required — saves boot space and weight | Required (or foam kit) |
| After puncture | Continue driving up to 80 km at ≤ 80 km/h | Must stop immediately |
| TPMS requirement | Mandatory — no tyre-pressure feedback without it | Recommended but not legally required everywhere |
| Ride comfort | Firmer; stiffer sidewalls transmit more road noise | Softer; more compliant sidewall |
| Purchase cost | 20–50% more expensive per tyre | Lower |
| Repairability | Most manufacturers advise replacement, not repair | Puncture repair often possible (if in tread area) |
| Weight | Heavier (reinforced sidewall) | Lighter |
Can you repair a run-flat tyre?
Most tyre manufacturers and vehicle OEMs state that run-flat tyres should not be repaired after a pressure loss event. The reason: when the reinforced sidewall operates at 0 PSI, internal heat and stress may cause invisible structural damage that cannot be assessed visually.
Some tyre shops will repair a run-flat if it has been driven under the speed/distance limits and the puncture is in the central tread zone (not the sidewall). However, any repair voids the run-flat warranty and is not recommended by most manufacturers. When in doubt, replace.
Can I replace run-flat tyres with conventional tyres?
Technically yes, but with important caveats:
- Your car was designed without a spare. If you switch to standard tyres, you have no fall-back after a puncture. You would need to carry a foam tyre sealant kit or portable compressor — neither replaces a spare for structural damage or sidewall cuts.
- TPMS is still mandatory. You will still receive pressure warnings.
- Suspension tuning on many run-flat-equipped cars is stiffer than average to compensate for the run-flat's stiff sidewall. Switching to softer standard tyres may make the ride feel bouncier or less planted in corners.
- If you switch, replace all four at once — mixing run-flat and conventional on the same axle is unsafe.
Do run-flat and conventional tyres wear differently?
Run-flat tyres typically wear slightly faster than equivalent conventional tyres due to the stiffer compound needed to maintain sidewall integrity. Expect roughly 10–20% shorter tread life in everyday driving. Tyre rotation every 5,000–10,000 km is especially important for run-flats to even out wear across axles.
More tools
- Tire type guide
- Tire pressure guide
- Tire tread depth guide
- Tire rotation guide
- Tire age guide
- Tire size calculator
- Tire & wheel reference guides
Seasonal check
Planning a long summer drive?
Use the budget and running-cost tools before a trip, especially if the current tyres are worn or the replacement size changes diameter.
What changed
- Reviewed deterministic geometry, load/speed references, sitemap inclusion and localized page shell.