Run flat tyres: Pros, cons and what are they?
Can you name one innovation that was bang-on perfect right out of the gate? I can’t either. Everything that is good now generally started as something rather rubbish, with the formula tweaked and teased until it was eventually just right.
We had to suffer through MiniDiscs to get to Spotify, for example. And if we weren’t willing to keep on evolving, we’d still be filling out Archie Query Forms online rather than Googling the web.
And so it was with the earliest iterations of run flat tyres (or run flat tires, for our American cousins). The idea was golden; tyres that, when punctured, didn’t immediately require changing, allowing you to drive on (albeit for limited kilometres and a limited speed) until you got home, or to your mechanic or tyre service centre.
While some feel comfortable changing a tyre at the side of the road, plenty don’t, and so the thought of being able to push on to your destination rather than be left waiting, often at night, for roadside assistance to turn up was a tempting one indeed.
And that’s without mentioning the amount of cargo space not carrying a huge full-size spare wheel can liberate, or the fact that goo-based puncture repair kits are the work of the devil, and are almost guaranteed to leave you with sticky hands, in a bad mood and with a still-flat tyre.
The only problem was, the technology didn’t quite match the sales pitch. On that rarest of rare occasions when you get a puncture (I drive a lot of cars, a lot of the time, and I honestly can’t even remember the last time I got flat tyre, but it would have to be at least six years ago), they were a life-saver, but the rest of the time, which is almost always, they tore away ride comfort and cabin ambience, with early run flat tyres feeling sharper and louder than their traditional counterparts.
Think of them, then, as a rolling version of Homer Simpson’s 'Everything’s Okay Alarm' (which would sound every three seconds unless something wasn’t okay). The pay-off just wasn’t worth the hassle. In fact, a JD Power survey from 2015 found owners saddled with run flats were less satisfied with them than traditional tyres, right across the board.
But there is no denying the fact the technology has improved, and continues to improve, with each passing year. The new Lexus UX, which touches down in Australia later this year, uses a new Bridgestone run flat tyre, chosen because the brand’s Japanese executives were chuffed at how little they impacted ride and handling compared to regular tyres. What’s more, they can be driven at up to 80km/h for up to 80km after a puncture.
So what are run flat tyres?
The technology was actually introduced in military vehicles around the time of WWII, with a bullet-proof lining used to ensure that, even if a vehicle has been shot at, its occupants could flee the area.
But run flat tyres prices ensured it wasn’t until decades later that the once prohibitively expensive concept trickled into passenger cars in any meaningful way, and later still (the 1990s) that they truly became a commonplace solution.
According to Bridgestone, there are two main types of run flat tyres in use today; a self-supporting version, and a support ring version.
With self-supporting tyres, the sidewall is reinforced in a way that it will hold its form, even if the tyre deflates. Essentially, the sides of the tyre (so not the part touching the road) are firm enough to hold their basic shape in the event of puncture. The support ring version uses a seperate ring of hard rubber, rather than the tyre itself, that comes into play when the tyre deflates.
Huge in Europe, almost all the major German brands now use them, with BMW run flat tyres used across the range, as well as run flat tyres fitted to Mercedes models, too. Audi, Lexus, and Mini run flat tyres are common, too.
Can I install run flat tyres on my car?
Short answer? Yes, you can. There are Pirelli run flat tyres, Continental run flat tyres, Michelin run flat tyres etc, and while all work slightly differently, they all serve largely the same purpose. There are no cheap run flat tyres, though; the most economical rubber you can fit to your car will be conventional tyres.
One important caveat, though; most experts suggest only fitting run flat tyres to cars with a tyre-pressure monitoring system. There are speed and distance limits on these types of tyres, and so it’s important to know when you have a loss of pressure.
Can I repair run flat tyres?
Yes and no, I’m afraid. The short answer is that, while the some punctures can be repaired (Michelin, says a run-flat can be repaired if the puncture occurs in the crown area, but cannot be fixed if the sidewall is ruptured or punctured), they’re not really built for that purpose.