A run-flat tyre is a pneumatic vehicle tyre that is designed to resist the effects of deflation when punctured. Several tyre manufacturers have developed run-flat tyre technologies. Run-flat tyres are handy when on a journey and you do not have a spare tyre. Subsequently, some vehicle manufacturers adopted this tyres as OE in a bid to increase customers satisfaction.
Self-supporting run flat tyre systems
The main type of run-flat technology in use today is the self supporting tyre. The tyre’s sidewall is reinforced to support the vehicle’s weight in the event of a flat.
Unlike other types of run-flats, this design allows tyres to be placed on any rim. The tyre is constructed with rubber compounds that prevent tyre destruction with excessive flexing, allowing a vehicle to brake, accelerate, and steer reliably for a given distance. *Reference to guidelines on individual tyre’s range of operation in the event of a flat, is required.
The diagram below shows a self supporting system developed by Dunlop.
Advantages of Run-flat tyres
- Safety
- With the RFT at high speed, you are able to control and drive the car to a safe location in the event of a puncture.
- You do not have the tedious or messy, in case of rain, and sometimes dangerous task of changing tyres, especially along highways, crowded or deserted roads.
- Convenience
- RFTs eliminate the spare wheel and tyre repair tools, freeing up extra space in the vehicle.
- No spare tyre theoretically means less vehicle weight and better fuel economy. But it’s not as much as you might expect because run-flat tyres weigh more than regular tyres due to the added sidewall reinforcement.
Disadvantages of Run-flat Tyres
- Typically costlier than conventional tyres. On average, run flat tyres are about 40% more expensive than regular tyres.
- They don’t provide as much grip in low temperatures.
- Studies show that people replaced their run-flat tyres sooner than owners using conventional tyres. Opinions differ on the reason, but one theory is that tyre makers put a soft tread compound on a run-flat tyre to counter the hard ride. A side effect of the softer compound is a shorter tread life. Actual data on the longevity of run-flat tyres have been hard to find. Owners reported higher overall satisfaction with run-flat tyres.
Concerns
- As of 2019, the run flat tyre market is mainly driven by car manufacturers and original equipment.
- Unreasonable tyre life and unexpectedly high replacement costs, has been observed, as compared to regular tyres.
- The safety benefits of run-flat tyres are arguably insignificant as to outweigh any possible trade-offs.
- Because run-flats aren’t a big-selling tyre, drivers shouldn’t expect to roll into just any tyre shop and buy one. If you’re a run-flat user on a road trip and get a flat, you’ll probably have to ground, waiting for the tyre to be shipped.
Make an Informed Purchase
Run-flat tyres seem to have more downsides than upsides, but many people swear by them. Take the time to seek customer reviews and know what tyres come standard on a car you are about to purchase.
Cautions
- A Run-flat tyre is not a “Puncture Free” tyre.
- Tyre repair is not recommended on RFTs for safety reasons, because no one can judge the degree of tyre damage after flat running.
- If original equipment is RFT, most probably the vehicle is not equipped with a spare tyre. In that case, replacement tyre should be ONLY RunFlat tyre for safety reasons.
- Run Flat tyres must ALWAYS operate together with tyre pressure monitoring systems. Since they do not bulge if the air pressure is low, the driver may never know they have a flat, which could lead to tyre failure.
- Most Run Flat tyres have a visible RFT logo on the sidewall for clear identification.