Monday, November 27, 2023

How Do Run Flat Tires Work

What Kind Of Vehicles Can Use Run

How Do Run Flat Tires Work

In theory, because run-flat tires have the same physical dimensions as conventional tires, any vehicle can use them. However, unless your wheels are designed for run-flats, they can overheat and separate from the wheel bead the same as a conventional tire when driving with low/no air pressure. In addition, because you may not recognize if one of your tires is flat, your vehicle needs a working tire pressure monitoring system . All vehicles that come with run-flats as standard equipment are required by law to come with a TPMS. If you plan to install run-flat tires on a vehicle that came standard with conventional tires, easily installed after market TPMS are available.

CAUTION: A brass valve core will corrode when used in an aluminum tire pressure sensor valve stem. Use nickel-plated valve cores with aluminum tire pressure sensor valve stems.

How Much Are Run

The added technology incurs added cost. Run-flat tyres tend to cost at least 50% more than their standard counterparts, with some costing twice as much.

Like standard tyres, the cost depends on the brand you choose and the size of tyre required. Theyre available from all the same suppliers, though: your main dealer, high street or independent tyre fitter or online suppliers.

Mixing Conventional Tyres With Run Flat Tyres

As a general rule of thumb, you should avoid mixing different tyre types on a vehicle. This is also true of combining conventional and run flat tyres on a car as their handling characteristics may differ, they should not be mixed on a vehicle.

If you’re looking for a wide range of tyres, use the search tool at the top of this page to see all of our in-stock options.

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Repairing Run Flat Tire

Unfortunately, these types of tires cannot be repaired, once they are used without air in the tubes. The reinforced walls of the tires become weak as they hold the weight of the car. The rubber in the support-ring-system might have got compressed by the weight of the vehicle. They just lose their structural strength. If repaired, they will get damaged. Also, remember that these tires are not perfect.

And that is why they cant be used in replacement for the older, conventional tires. The conventional tires can all be repaired easily and cheaply. Since run flat tires are more expensive, just imagine, a driver will have to buy a new tire every time there is a puncture.

How To Identify Run Flat Tyres


You can identify whether your tyres are run flat by inspecting the tyre sidewall. Unfortunately, there is no standard code used for run flat tyres and different tyre manufacturers use different symbols. Please see the table below for the run flat codes for specific tyre manufacturers. If you are looking at purchasing run flat tyres on the National Tyres website, you will be able to filter to only show run flat tyres. Within the search result, any tyre marked with the tyre symbol ‘RF’ is a run flat tyre.


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What Is A Run Flat Tire And How They Work

Although they first hit the market in the mid-1980s, run-flat tires are more popular today than ever. As some automakers make them the standard for new vehicles, more and more consumers are asking about run-flat levels, their benefits, and how their use affects driving.

A flat tire often happens at the most inopportune time or place. Most people may call roadside assistance, but theyll likely be waiting about 45 minutes to an hour. If you know how to change the spare, its a dirty job, and chances are youre not properly dressed for it. Worse yet, your car may have no spare tire, and you might not know how to use the tire repair kit.

Enter the run-flat-tire. Run-flat or zero pressure tires can support the weight of a vehicle for a short period of time and give the driver about 100 miles of range to find a repair shop. While it sounds like the perfect solution, car owners and car buyers should be aware of the tradeoffs.

Run-flat tires are standard on 14% of new vehicles. While the number of vehicles with run-flat tires has doubled over the past decade, they seem to have hit a plateau. The total percentage of vehicles with emergency run-flat has risen to 13 to 14% in the last five years. Most vehicles from BMW, Mercedes-Benz, and Mini now have run-flat-tire. Cadillac sedans also use run-flat tires.

What Are Run Flat Tyres

With Run-Flat Technology tyres, you can continue driving after a puncture so you make your way to a workshop or find a safe, level area to change your tyre.

You cant drive on them indefinitely, though. Check the manufacturers specifications to find out how fast and how far you can drive on your RFT tyres. Bridgestones RFT tyres will allow continued operation even after a loss of some or all inflation pressure for up to 80 km at a maximum speed up to 80 km/h.

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What Is The Purpose Of A Run

A Run-flat tyre allows you to continue driving for a while longer after it has been punctured, with the purpose of getting you to a safe place rather than being stuck and worried. Due to their unique construction, they also minimise the potentiality of rapid, explosive tyre pressure loss commonly known as a blowout.

How Long Can I Drive With A Punctured Run

DriveGuard – Run-Flat Technology

Regular tires need air to support the weight of your vehicle. Bridgestone notes that run-flat tires are no different in this regard, but everything changes when the tire gets a puncture. With a regular tire, your car is immobile until the tire is changed. But with run-flats, you can continue driving presumably enough to get you home or to the nearest garage, Bridgestone explains.

Another common question is how to know if your run-flat tires have a puncture. Since run-flats would still look inflated even with zero air pressure, it may be tricky to know if your run-flats are punctured or losing air. It’s the reason run-flat tires are only compatible with vehicles that come standard with a tire pressure monitoring system from the factory, as Bridgestone noted. You will also feel a thud and a vibration, according to Bike Hike.

Tire manufacturers use the same materials from common tires in making a run-flat tire, so the wear rates should be comparable, though a J.D. Power study noted by Edmunds found that some users replace their run-flats up to 6,000 miles sooner. Don’t ignore the low tire pressure warning sign, which lights up if the tire needs air. Even though run-flat tires can operate without air, as Bridgestone noted, keeping the correct tire pressure at all times will ensure steady rolling resistance and longer wear life.

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The Pros And Cons Of Run

Do you need to change the tires on your car? Do you want to improve your driving safety? Although they are not famous to most motorists, it is interesting to discover run-flat tires, a range beyond traditional car tires. Let’s discover through this article its advantages and disadvantages.

Even when their use has good advantages, such as increased safety and increased rear trunk loading volume because of the absence of the spare tire, they also attributed some disadvantages to them. Indeed, they reduce ride comfort and are more expensive to replace.


What Happens When A Run Flat Tire Gets A Puncture

In an ideal scenario, a self-supporting run flat tire would be able to continue driving and support the weight of a vehicle due to the reinforced sidewall.

For an auxiliary-supported run flat, the weight of the flat tire rests on the backup’s treads. According to, that shifts the mechanical responsibility of driving on a run flat to the more-sturdy wheel, lifting some of the burden off of the tire itself.

If a self-sealing tire gets a puncture, it depends on if the object sticks to the tire or not. If it remains, the compound forms around the obstruction and seals it off from the rest of the tire. If it doesn’t stick, the sealant forms around the hole.

How soon after a puncture do you have to change a run flat tire?

Every tire manufacturer recommends that when arun flat system is being used, you should use the limited distance it affords you to reach a mechanic or tire shop for an immediate replacement.

Keep in mind that while 50 miles and 50 mph is the recommended distance and speed of a run flat tire, it’s ideal to keep speeds lower and the distance you have to drive shorter to have a better chance of not having a full blowout.

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Why Are Manufacturers Ditching Spare Tires

Car manufacturers claim that they are reducing weight and space consumption by removing spare tires from cars. While this sounds logical in theory, spare tires dont necessarily add that much weight to a vehicle. In fact, unless you are driving a race car or performance-oriented car, the additional weight of having a spare tire does very little to affect your cars driving ability or fuel economy.

Spare tires are also kept in places where you wouldnt typically store cargo, sometimes even being attached to the underside of the car. On Jeeps and trucks, the spare tire is entirely external, and even part of the iconic design. For cars and SUVs, the spare tire is hidden under the trunks floor, not really where you want to put your groceries or gym bag anyways.

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How Much Do Run Flat Tires Cost

How Do Run Flat Tires Work?

Depending upon the manufacturer, run-flat tires can cost between $150 to $500 per tire, or 35% to 200% more than a traditional tire.

Run-flats are also more difficult to repair than regular tires and usually need to be replaced if they are damaged. Regular tires can often be patched, which costs significantly less than full replacement.

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Can I Swap Run

Yes, although its a good idea to check with the manufacturer first, as your cars suspension may have been configured specifically to work with run-flats.

Its also important to note you should never mix run-flats with conventional tyres, so youll have to swap all four at the same time.

Also make sure you buy a spare wheel, jack and wheel brace when you make the change. If there isnt anywhere to put these, youll have to make do with a can of tyre sealant and a compressor although there are limits to the types of puncture tyre sealant can fix.

Some Carmakers Fit Run

Along with flat batteries, flat tyres are one of the biggest causes of roadside breakdown callouts in the UK.

There are many reasons why someone may experience a puncture. Old tyres, damage from a poor road surface or pothole, a rogue sharp object, or a faulty inflation valve are just some of the potential causes.

Unfortunately, fewer cars are now fitted with full spare wheels as standard and not all motorists know how to change a tyre. However, there is another option – the run-flat tyre.

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Cons Of Run Flat Tires

  • High Price: Drivers will pay more for their specialized design. Compared with prices on regular tires, run-flat tires can cost you anywhere from 35% to 200% more, or between $150 and $500 per tire.
  • Few options: Compared with the buffet of choices you get when choosing regular tires, there are limited options for run-flats.
  • Harsh ride quality: Due to the stiff design of a run-flat tire, drivers are more likely to feel bumps in the road.
  • High repair cost: While regular tires can often be patched, run-flat tires typically need to be replaced if they are damaged. And since tires should be replaced in pairs, it can cost twice as much for repairs.

How To Identify Run

Do Bridgestone DriveGuard Run Flat Replacement Tires Work? | Consumer Reports

Modern cars that come with run-flat tires dont have a spare tire in the boot. So if you notice that you dont have a spare tire, your car could have run-flats. BMW and Lexus are manufacturers that most commonly fit run-flat tires across their range

You can also identify a run-flat tire based on the code written on the tire sidewall. However, since there is no standard code for this type of tire, it can vary between manufacturers. Below are some of the codes found on run-flat tires.


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My Run Flat Tire Has Been Punctured How Long Can I Drive On It

Run flat tires only allow you to drive for a limited distance and reduced speed after a puncture or other event has resulted in either a drop in tire inflation pressure or a complete loss of inflation pressure. If you have MICHELIN® Zero Pressure tires, you can drive up to 50 miles at 50 mph with a flat tire.

Can You Replace Run

On a vehicle fitted with original equipment run-flat tires, the manufacturer has adjusted the suspension to suit the tires. Therefore, its often not recommended to install regular tires on vehicles designed to use run-flats. That said, it is indeed possible. If you do choose to replace your run-flats with regular tires, be sure to choose tires with the correct size, speed rating, and load index. You should also replace all four tires and not mix run-flats with regular tires. Also, dont forget to carry a spare tire and tire changing kit in your vehicle.

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Can You Repair Run

Official advice regarding the possibility of repairing run-flat tyres varies. The British Rubber Manufacturers Association, a group representing the major tyre manufacturers, does not recommend repairs to a run-flat tyre.

Tyre speed rating and labelling guide

Confusingly, theres less agreement among individual tyre manufacturers: some say repairs are fine under certain conditions, or as long as the work adheres to British Standard BS AU 159. Others say the tyres should not be repaired and instead should be replaced immediately. Speak to your tyres manufacturer for more information.

Either way, you may find it hard for a reputable tyre retailer to repair rather than replace a run-flat tyre. According to the UKs Tyresafe organisation, even qualified tyre repairers may not be able to detect damage to a tyre. Kwik-Fit and National Tyres, two of the UKs largest tyre retailers, say they will not carry out run-flat repairs.

How Long Can You Drive On Run


Run-flat tires cannot be driven faster than 50 miles per hour and typically offer up to 50 miles of extended mobility. Selected applications, based on vehicle and the run-flat tire design, can range from just 25 miles up to 200 miles. Consult your vehicle owners manual to determine what you should expect.

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Can Run Flat Tyres Be Repaired

If you have checked your tyre and discovered a puncture, you may be thinking about having it repaired. In line with most leading tyre retailers, National Tyres will not repair a run flat tyre following a puncture. Most manufacturers advise against repairing run flat tyres. If the deflated tyre has been driven on, it could have compromised its strength, and it is impossible for a fitter to know if the tyre was driven on for longer/faster than recommended after a puncture. For a brand-specific answer, you can contact the manufacturers below, but generally, it will be hard to find a retailer who will be willing to repair a run flat tyre.

Why Change From Run Flat To Conventional Tyres

We are not recommending that you change the type of tyre your vehicle was originally supplied with. Changing to normal tyres could affect the handling of your car, so you must always consult the manufacturer before making this type of change.

However, some people choose to do this for the following reasons:

  • Conventional tyre prices are generally cheaper than run flat tyres and have better availability
  • There is a wider range of standard tyres available, ranging from cheap tyres to premium tyres
  • Some drivers find that conventional tyres give a smoother, less bumpy ride than run flat tyres
  • In line with most leading tyre retailers, National will not repair a run flat tyre following a puncture

At National, you can purchase runflat tyres either online or at your local branch. We stock run flat tyres to suit a wide range of vehicle manufacturers, including BMW run flat tyres, Mercedes run flat tyres and many other vehicle manufacturers.

To find the perfect runflat tyres for your vehicle, please enter your vehicle registration number or tyre size into the search box at the top of this page.

See below for some industry views on this subject **

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Fitting Run Flat To An Older Vehicle

If you are considering changing to run flat tyres on a vehicle that was previously fitted with ‘normal’ tyres, then there are several points to consider:

  • Tyre Pressure Monitoring SystemRun flats must only be installed on a car which has TPMS/tyre pressure monitoring system. TPMS alerts the driver to a puncture so they are aware that they have a limited time to replace their tyre, and so they drive within the limits of their deflated tyre
  • Vehicle Suspension You should also note that you may need some changes made to your vehicle’s suspension. Because of their stiffer construction, run flat tyres contribute to a vehicle’s suspension when fitted as original equipment.
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