Runflat (RFT) vs. Regular Tyres: Pros, Cons & Fitment on Aftermarket Wheels
WHEELS 'N CUSTOMS
TECHNICAL GUIDE: RUNFLAT (RFT) VS. STANDARD TYRES
Runflat (RFT) vs. Regular Tyres: Advantages, Disadvantages & Fitting to Aftermarket Wheels
Many modern cars – particularly models from BMW, MINI and Mercedes-Benz – are delivered from the factory fitted with Runflat tyres (RFT) as standard. The main advantage is clear: with a puncture you do not need to dangerously change to a spare wheel at the roadside, but can continue driving at a reduced speed to a safe location or garage. The manufacturer also saves on the weight and space of a spare wheel or jack in the boot.
When car enthusiasts switch to a new set of exclusive alloy wheels, there is invariably debate about this tyre technology: "Can regular (non-runflat) tyres be fitted to wheels that previously had runflats?", "Why does a runflat tyre feel so much stiffer than a standard tyre?" and "May I fit runflat tyres to a car without TPMS sensors?" In this technical guide the specialists at Wheels 'N Customs explain all the advantages, disadvantages, carcass structures and safety requirements for you.
1. The Technology: Self-Supporting Sidewalls (Self-Supporting Tyres)
The vast majority of modern runflat tyres operate according to the so-called Self-Supporting Tyre (SST) principle. Whereas a standard car tyre will completely collapse and roll off the rim when air pressure is lost, a runflat tyre has a mechanically reinforced sidewall:
Reinforced Rubber Inserts
The sidewalls of a runflat tyre are fitted with extra-thick rubber inserts and heat-resistant cord layers. At 0 bar air pressure these stiff sidewalls carry the full weight of the vehicle without collapsing.
The 80 / 80 Mobility Rule
In the event of a complete loss of pressure the tyre manufacturer guarantees that you can still drive up to a maximum of 80 kilometres with a maximum speed of 80 km/h. This ensures you can always reach your destination or workshop safely.
Brand Codings on the Sidewall
Each brand uses its own coding: RFT (Bridgestone), SSR (Continental), ROF / EMT (Goodyear), ZP (Michelin Zero Pressure), Pirelli Run Flat or HRS (Hankook).
2. Why Does a Runflat Ride Stiffer? (Unsprung Mass)
The biggest drawback of runflat tyres is the noticeable effect on ride comfort and driving dynamics:
Loss of Natural Sidewall Damping: With a conventional tyre the elastic air chamber combined with the flexible rubber sidewall acts as the car’s first damping element. Because the sidewalls of a runflat tyre are extremely stiff, they hardly flex. Short imperfections, transverse ridges and speed bumps are transmitted unfiltered to the chassis and steering wheel.
Higher Unsprung Mass: Due to the massive rubber layers a runflat tyre typically weighs 1.5 to 2.5 kg per wheel more than a standard tyre of the same size. An increase in unsprung and rotating mass worsens the responsiveness of the shock absorbers, increases rolling resistance and makes the steering feel more sluggish.
More Prone to Ruts: The inflexible sidewalls of an RFT tyre tend to follow ruts and rutting in the asphalt (such as truck ruts in the right lane) directly, forcing the driver to make steering corrections more often.
3. May You Use Runflat Tyres Without TPMS? (Extremely Dangerous!)
The answer is clear: No, fitting runflat tyres to a car without an active tyre pressure monitoring system (TPMS) is strictly prohibited and life‑threatening.
Why is driving without TPMS with runflats so risky?
With a conventional tyre you notice immediately when it goes flat: the car pulls, the steering becomes heavy and the rim drops towards the road. With a runflat tyre you will notice absolutely nothing when it loses all pressure (0 bar) when driving straight, because the sidewall does not collapse!
Undetected Pressure Loss: Without a warning light from the TPMS sensor, the driver may continue at 120 or 130 km/h on the motorway.
Internal Friction Heat: Because the tyre rests on the rubber inserts without air pressure, extreme internal friction heat builds up at high speeds.
Catastrophic Blowout: The internal rubber overheats and disintegrates after tens of kilometres at high speed, after which the tyre suddenly bursts (blow‑out) with potentially fatal consequences.
If your vehicle did not leave the factory with an active or passive TPMS system, you must under no circumstances fit runflat tyres.
4. Fitting on Aftermarket Wheels: What Fits What?
There are two frequently asked fitment questions when changing wheels:
Question A: Can standard tyres be fitted to original Runflat wheels?
Yes, this is 100% safe and requires no modification!
Many BMW and Mercedes drivers switch from runflats to high‑quality standard tyres (non‑RFT) when replacing tyres. The car immediately feels quieter, rides softer over ridges and steers lighter. Tip from Wheels 'N Customs: when switching to standard tyres always keep a tyre repair kit (12V compressor + liquid tyre sealant) in your boot, since the car has no spare wheel!
Question B: Can Runflat tyres be fitted to Aftermarket wheels?
Only if the wheel is compatible (EH2 / Extended Hump)!
Original runflat wheels have a special raised rim flange in the wheel bed, the EH2 (Extended Hump) or EH2+. This raised flange prevents the extremely stiff bead of an uninflated runflat tyre from slipping into the deep centre of the rim in a sharp corner. Standard aftermarket wheels often have a regular H2 hump; modern runflats can be mounted on these, but require special tyre‑changing machines with plastic protective claws to avoid rim edge damage.
5. Comparison Table: Runflat vs. Standard Tyres
Feature
Runflat Tyres (RFT)
Standard Tyres (Non‑RFT)
Safety When Punctured
Excellent (80 km run‑flat at 0 bar)
Immediate stop; risk of rim damage
Ride Comfort & Rolling Noise
Stiffer, harsher over bumps, more rolling noise
Optimal comfort, quieter and smoother damping
Weight per Tyre
1.5 to 2.5 kg heavier (unsprung)
Significantly lighter (better response)
Repair After Nail / Puncture
Almost NEVER allowed (replace immediately)
Easily repaired with a plug/patch
Purchase Price
Approx. 20% to 40% more expensive per tyre
Cheaper and a much wider selection
TPMS Sensor Requirement
100% LEGAL & TECHNICALLY REQUIRED
Legally mandatory for cars after Nov 2014
Why can a Runflat tyre not be repaired after a puncture? Almost all leading tyre manufacturers (including Michelin, Continental and Bridgestone) prohibit vulcanising or plugging a runflat tyre that has been driven on with too low pressure. Because the reinforced sidewall becomes extremely hot at 0 bar, the internal carcass structure can be invisibly weakened. A repaired RFT tyre can still burst suddenly at high speed later on.
Professional Tyre Fitting & TPMS Relearning in Nijkerk
Whether you want to switch from stiff runflat tyres to comfortable standard tyres, or need a scratch-free fitting of your tight runflat wheelset, our workshop in Nijkerk has special arm-mounted demounting equipment for stiff carcasses, precision wheel balancers and advanced diagnostic equipment to programme your TPMS sensors fault-free on the spot.
Unsure whether your aftermarket wheels are suitable for runflat, or want to know which standard tyre offers the best comfort? Our specialists will be happy to advise you personally.
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