Run On Flat

26 May 2016

Replacing a flat tire with the spare one is often a nightmare, especially if you're a women or (to avoid getting accused of a misogynist attitude) if you're a man and outside, the heavy rain makes an umbrella a waste of time. But even so, most cars are equipped with a spare tire and every driver, more or less experienced, has to have the know-how to replace a flat tire. Somehow, every driver out there learns, sooner or later, forced by such an event or voluntarily, to do it.

But companies out there, and especially tire makers, have developed a better way to get rid of this whole annoying process: they developed the so-called run-flat tire, that allows you to drive the car even if the tire got punctured. But before rushing into details, let's take some history lessons and find out how did the run-flat tire enter the automotive world.


The run-flat tire is actually a more than 30-year old concept, but the technology can be traced back to 1892, when the first patent was officially registered. Even if developments in this area continued through years, the first tire maker to come up with a flat-tire was Goodyear in 1978. Obviously, the first projects were far from being efficient, so only a few prototype vehicles got equipped, at that time, with such a tire.

Nevertheless, the demand for a spare tire replacement increased continuously so the first production model featuring a run-flat tire saw daylight in 1994. It was a Chevrolet Corvette and was only offering the run-flat tire as an option.

Wondering why was the Corvette the first to offer such a system? Well, mostly because these two-seater didn't offer too much luggage room, so a spare tire – plus the adjacent tools required to change a flat tire - was obviously a waste of space. By 1995, all Corvettes were sold with a run-flat tire as standard.



Run-flat tires are working on a simple principle: once the “system” - we'll call it like that because the tire is usually closely working with the wheel to cope with the air pressure loss – detects the first signs of deflation (usually caused by punctures), it automatically applies a number of counter-effects to ensure safety and continuous driving.

In most cases, the run-flat tire allows you to keep driving for a limited distance, although this depends on the manufacturer. For example, some tires are especially designed to provide a 100 miles (around 161 km) range, while others could cover up to 200 miles. However, once the run-flat 

“system” is activated, the driver must be extra-cautious and keep the speedometer at low speeds – often below 90 km/h.

There are multiple types of run-flat tires out there.

First of all, we have the ones that are self supporting the weight of the car in the event of a puncture. The stiffer side-walls are thicker than on regular tires, thus allowing the tire to cope with the weight of the vehicle and provide continuous driving. As a general idea, this tire's side walls are made of an extra layer supported by a heat-resistant cord, that keeps the tire in the original position even under the weight or road bumps.

Secondly, there are a number of products which are offered with a backup layer which, in case of a puncture, it automatically seals the hole and minimizes the loss of air. Obviously, this type is less efficient as it still allows the air to get out of the tire – until the seal comes into effect. Additionally, it could fail to stop the deflation completely but still, it could allow the driver to reach the first service center.

Opinions are still divided when it comes to the use of run-flat tires. Some people find them extremely useful – as they ensure safety while driving for several hours – while others are talking about them as a waste of time and money.

The first consequence of using a run-flat tire is that, once it comes into effect, you'll have to reduce speed and drive carefully (this is a main demand when getting behind the wheel in the first place). However, for some drivers, especially those with less experience, driving with a run-flat tire could cause mental or emotional stress which, in some cases, could lead to other problems and have serious consequences on both the driver in question or the other motorists on the road.

Another result of such a tire is brought by the increased weight. A heavier tire could translate into reduced engine performance, increased fuel consumption – or lower fuel efficiency, if you prefer – and, in some cases, reduced braking performance. The latter is obviously the most important but, thanks to some new developments in the run-flat technology, this is slowly getting solved.

The cost is another important aspect of a run-flat tire. Installing such a tire is obviously more expensive than fitting the car with regular ones, thus raising the overall price of the car. Furthermore, repairing/replacing a run-flat tire that got damaged after using it is again considered too costly in many cases.

On other hand, using a run-flat tire could save your life. Imagine the following scenario: you're driving on the highway and a puncture occurs. In the case of a regular tire, the blow-out could have serious consequences as, in most cases, the driver loses control of the car completely and the only thing he's left with is the Bible (if he's lucky enough to carry it within the glove compartment). The run-flat tire protects the car and maintains handling in the aforementioned scenario, although it requires you to reduce speed.

A run-flat tire is usually requiring a Tire Pressure Monitoring System, which will in turn allow the driver to find out whenever the puncture occurs.

Additionally, the absence of the spare tire means more luggage space so the driver could use the additional room for other purposes (women for instance could carry, when going into a two-day holiday, enough clothes for more than a week). Another thing worth mentioning is that carmakers could use the space provided by the lack of a spare wheel for future technologies, such as hybrids or electric cars, that require a battery to be fitted in the trunk.

Through time, run-flat tires are growing in popularity but even so, the disadvantages we told you about are convincing both automakers and buyers to avoid adopting this kind of systems. However, analysts are expecting the run-flat tires to become a must have in the future, mostly because people are rating safety and comfort as two main factors when buying a new car. And a run-flat tire is mostly about these two things.