Run-flat tires – how do they work and are they any good? | Rpmgo.com



Perhaps some of the most important parts in any car are the tires, because, obviously, they are what keeps your precious vehicle going on the road.

We’ve already talked about the various advantages and disadvantages of certain types of tires, all-season, summer and snow ones, in various conditions. Now though, we’ll tackle a new type of tire technology, which is slowly becoming more and more present on the roads: run-flat tires.

Hit the jump to find out how they work and, more importantly, if they are any good.

Now I don’t know about you, but when I think about run-flat tires, my mind jumps to secret agents in Aston Martins, high level dignitaries or perhaps even dictators, which need their vehicle to keep going no matter what. These days though, your mind should be jumping to quite a few other vehicles, including even Mini or BMW models, as they are also starting to feature run-flat tires as standard equipment.

So, how do run-flat tires work?

First off, there are three types of run-flat tires, although only one is predominantly used, while another more or less cheats to get the same results. The first are self-supporting run-flat tires which, you guessed it, support themselves in the case air is leaking out and causing it to deflate. Because these types of tires have stiffer side walls (due to the addition of thick layers of rubber and cord), they can provide support for the car at speeds of up to 55 mph and for around 50 miles on average.

The second type are self-sealing run-flat tires, which, once again pretty obviously, seal themselves up in case of a puncture. There are two such tire types. The first can be specifically built with an extra layer of insulation on the inside that either seals the puncture permanently or just prevents air from getting out as fast as it normally would. The second can see a regular tire transformed into a self-sealing one thanks to the insertion of special sealants, most often through the air valve. The regular motions of a tire distribute the sealant throughout the surface of the tire, and prevents it from loosing air.

Last but not least are auxiliary-supported tires which feature an additional ring on the wheel, which can supports the weight of a car for a certain distance at up to a certain speed. This is basically the opposite of self-supporting run-flats, as they don’t use the stiff side walls but the ring in question. Due to their more expensive nature, such types aren’t that popular these days.

That was how run-flats work, but I’m sure many of you are interested to see if they are any good.

First off, the major advantage to such tires is, of course, safety. You won’t loose control in case of a puncture at high speeds, and you can keep going until you find a specialized service where they can fix it up. As such you prevent the need to stop by the side of the road, which isn’t too safe, and change the tire.

As you can imagine, using run-flat tires eliminates the need to have a spare one in the trunk, meaning more space to be used by extra cargo, or in case of hybrids and electric cars, to be used by batteries. The lack of a spare also means a reduction in the curb weight of the car, which is great for sports ones.

But don’t go buying run-flats just yet, as they are still a bit more expensive than regular ones, and not every auto shop knows how to fix them once they were punctured. The performance of the run-flats isn’t all that great either, especially for self-supporting ones, which are stiffer, so put off those extended drifting sessions for now. Complaints of increased noise output and the fact that they aren’t really good with potholes have also been recorded.

In the end, it’s your choice. Considering the big number of accidents caused by ruptured tires, run-flats might be a safe investment. Also, as carmakers are beginning to adopt them in higher numbers, they might become an integral part of out driving experience.

This has been a part of our weekly RPMGO Answers feature, where we take different automotive-related questions and try to find the simplest answer. You can check out other questions in the dedicated RPMGO Answers section.

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