The Truth About Run-Flat Tires

Picture this: you’re driving alone in an unsafe area, and one of your tires blows out. You don’t want to pull over to take off your punctured tire and put on a spare, you want to get to a safe location to take care of it. What do you do? If you’re driving on a run-flat tire, you have an advantage in this situation.

What are Run-Flat Tires?

Run-flat tires are tires that are reinforced to be able to function normally for a limited distance, giving you the ability to get to a tire dealer for a replacement without the hassle of changing to a spare or dealing with the expense of a tow truck, and without the dangerous loss of handling that a flat tire causes.

Run-flat tires are also called Zero Pressure tires, because they are constructed to be able to be used in cases of lost tire pressure. In a normal tire, the air pressure within the tire supports the weight of the car, however although run-flat tires will still be filled with air, if there is a puncture the construction of the tire itself can support the weight of the car for a short time.

There are two main types of run-flat tire: Self-Supporting, which uses reinforced sidewall construction, and Support Ring, which features a hard rubber ring or similar type of structure within the tire, both of which can support the car’s weight if the tire loses air pressure due to a puncture.

How Far and How Fast Can You Drive on a Run-Flat Tire?

Run-flat tires are designed to support the weight of a car, and maintain driving stability and handling in the case of a puncture, however they are not made for long-term use. You can find out the safest distance and speed to drive on a punctured run-flat tire by checking with that tire’s manufacturer recommendations. However, depending on road conditions and weather, it could vary, as bad road conditions or severe weather could reduce the length of time it is safe to drive on the tire.

An accepted rule-of-thumb is that a punctured run-flat tire is good for about 50 miles, driven at a maximum speed of about 50 miles per hour. This allows time to drive somewhere safe to get the tire replaced.

Can Run-Flat Tires Be Repaired?

While some sources say that damaged run-flat tires may be inspected to see if damage can be repaired, the general consensus is that they should not be repaired and must be replaced if they are damaged. This is because they are only designed to support the weight of a vehicle for a temporary period of time.

Driving on the tire while punctured may be able to get you safely to a repair shop, but the internal construction of the tire, the very thing that was able to support all that weight, becomes worn down and compromised. This makes it unsafe to repair and reuse that tire, risking the chance that it could not support the car safely a second time if another puncture occurs.

It’s important to note that run-flat tires should always be used on cars with Tire Pressure Monitoring Systems (TPMS). This is because if a run-flat tire is punctured, the run-flat tire will keep the car driving normally, and the driver may not notice in time to get the tire replaced before it fails. If a car has a TPMS, it will alert the driver in the instance of a tire puncture and loss of air pressure, leaving time to take action before the situation becomes dangerous. 

Some Pros and Cons of Run-Flat Tires

The benefits of run-flat tires seem fairly obvious; convenience and increased safety and potentially less cargo weight, as car owners could skip carrying a spare tire and tire replacement tools.

However, there are some trade-offs that drivers should consider as well. For example, because of the extra structure of run-flat tires and the materials used, they can be much more expensive than regular tires. Due to the rigidity of their sidewalls, drivers with run-flat tires sometimes complain of a bumpier, more noisy ride than standard tires. They are also heavier than regular tires, which can affect gas mileage, and some drivers complain that for this reason they get fewer MPG (miles per gallon) than with regular tires.

As mentioned earlier, in cases of a puncture, most run-flat tires cannot be repaired and must be replaced. And while run-flat tires are becoming increasingly popular, they are typically not available in as wide a range of tire sizes as standard tires come in.

Conclusion

In this blog, we wanted to give you an overview of the most important things to know about run-flat tires, whether you currently drive on them, or are considering installing them. Take a look at some of our past blogs on similar tire topics, and sign up for the Tire Research email list to get monthly tire articles and tips sent directly to your inbox.

Wondering how often you should change your tires? Find out in our previous blog:

How Often Should You Change Your Tires?

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