Although they first hit the market in the mid-1980s, run-flat tires (RFT) 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 they’ll likely be waiting about 45 minutes to an hour. If you know how to change the spare, it’s a dirty job, and chances are you’re 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.
Run-flat tires are tires on which you can continue driving after a puncture so you can take the time to get to an auto shop or find a safe, level area to change your tire.
However, you cannot drive it indefinitely. Check the manufacturer’s information to find out how fast and how far you can go with your run-flat tires. These flat tires allow continued operation even if some or all of the tire pressure is lost for up to 80 km at a top speed of up to 80 km/h.
There are two primary types of run-flat tire systems: the self-supporting system and the support ring system.
In most self-supporting run-flat systems, the tire has a reinforced sidewall construction that continues to support the vehicle in the event of a loss of air. This design allows continued operation after the air pressure has been depressurized up to the manufacturer’s specified speed and distance.
Support ring run-flat tire systems, on the other hand, employ a ring of hard rubber or another structure that can support the vehicle’s weight in an air loss condition.
Since they continue performing even though they’re “flat,” all run-flat tires, regardless of the specific system type, may only be used on a vehicle equipped with a Tire Pressure Monitoring System (TPMS). The TPMS alerts you as soon as one of your tires loses pressure. Without it, you might not know you were driving on an underinflated tire.
if you still got a flat tire, there is no consensus on whether or not run-flat tires can be repaired. Tire manufacturers often defer to the vehicle manufacturer’s replacement tire restrictions and recommendations.
Michelin North America Inc., for example, allows its run-flat tires (Zero Pressure) to be repaired under certain guidelines. However, repairing the original equipment run-flat tires on a BMW isn’t an option, per its owner’s manual.
As consumers continue rating safety high on the list of features they look for in a vehicle, the popularity of run-flat tires is expected to grow. Since run-flat tires work reliably with interconnected technologies like TPMS, it may only be a matter of time before they become the norm rather than the exception in new vehicles.
The most common type of run-flat technology today is the self-supporting tire. The sidewalls of the tire are heavily reinforced to support the vehicle when the air pressure is low or when the tire has lost all of its pressure.
A self-sealing tire isn’t a run-flat tire in the sense that it can operate without air. Instead, it has a layer of sealant inside the tire that can maintain the air pressure in the event of a puncture. If you get a nail in the tire and remove it, the sealant will fill the puncture as long as it is near the center of the tread and is not larger than 5 millimeters.
The biggest advantage of the self-sealing tire is that it resembles a traditional tire. It can be mixed and matched with standard tires, and the tread life is the same. The downsides are the higher cost (roughly the same premium as a run-flat tire) and restricted availability.
This type of tire isn’t standard on new vehicles but is worth mentioning since it is available as a replacement tire.
Run-flat tires are tires on which you can continue driving after a puncture so you can take the time to get to an auto shop or find a safe, level area to change your tire. You can’t drive on them indefinitely, though.
Unlike conventional tires, which require air to stay hard, run-flat tires have a reinforced sidewall, meaning they stay rigid without any air pressure. The reinforced outer shell of run-flat tires keeps the rubber in place without air, supporting the car as you continue your journey.
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 owner’s manual to determine what you should expect.
Typically, Run Flat Tires cost about $200-$500 per tire for a passenger vehicle, or about 50-200 percent more than standard tires. The best benefit when it comes to cost comes from the fact that these tires can outlast several tire changes. It remains affixed to the wheel within the tire.
You can usually tell if your tires are run-flat by looking at your tires, or by examining other details about your car. Find the words “Run Flat”, “SSR”, “HSR”, “RF”, “Run on Flat”, “ZP”, “DSST”, “RFT” on your tires.
Run-flat tires are more expensive to replace. Prices will vary by tire type and purchase location, but it’s not uncommon to pay a $40-$65 premium for a run-flat-tire. Also, many run-flats cannot be repaired and often need to be replaced in pairs.
Continued innovations have expanded the offerings to include the three types of run-flat tires, distinguished by their methods of protection.
Yes, you can replace four run-flat tires with four conventional tires as long as they meet your vehicle’s manufacturer’s recommendations. Keep in mind that different tires are designed to deliver different results.
Doing this can prevent any form of permanent damage to both the rim and tire. In the unfortunate event of not being able to repair the tire immediately, the next best thing to do is to elevate the edge of the car with a jack.
No. Do not drive on a flat tire. However, it may be necessary to travel a short distance on a flat tire when pulling over to the side of the road. But driving on a flat tire is a surefire way to put your passengers at risk and seriously damage your vehicle.
Run-flat tires are engineered for drivers of performance sedans and coupes with a special tread compound designed to handle winter temperatures. They deliver impressive grip and control on wet, dry, icy, slushy, and snowy roads while also giving you a comfortable and dependable ride.
Most run-flat tires will usually run on for at least 50 miles at a reasonable speed, certainly long enough to organize a safe replacement in all but the most unusual situations.
In a deflated run-flat tire the internal flexing generates lots of heat, which destroys both the rubber and the underlying steel-and-fabric structure. Drive Guards to feature something called cooling fins molded into the sidewalls to disperse heat. Still, they’re pretty much toast after 50 miles.
Run-flat tires are OEM equipment on many new cars and they’re an important safety feature. But they can give a stiff and bumpy ride, they’re more expensive than conventional tires and they can’t be repaired meaning you will have to replace them after a puncture.
RFTs wear out an average of 6,000 miles before standard tires. While some manufacturers say it may be OK to repair RFTs in some circumstances, driving any distance on a flat RFT can damage the internal construction of the tire. No type of tire should be run when it is very low on air pressure.
M+S stands for Mud + Snow, indicating that the tires are suitable for use in the winter (studded or non-studded winter tires). The official winter tire marking is the snowflake symbol, also known as the 3PMSF marking.
In order to slash a tire quickly, you need to use a sharp knife instead of a usual household one. A knife can very easily poke the rubber surface if applied with adequate force. A true knife slash will render the tire flat in a matter of seconds.
Run flats are only fitted to new cars which have a tire pressure monitor system (TPMS). This senses when there is a puncture in a run-flat tire and produces a warning on your vehicle’s dashboard. For this to be accurate, you need run-flat tires on all wheels.
Almost all of the mainstream tire brands now sell some form of run-flat, including Pirelli, Bridgestone, Continental, Dunlop, Michelin, and Goodyear.
Modern run-flat tires don’t need special rims, but they are only functional on cars that are equipped with a working air pressure control system.
Common BMW tires are priced between $150 – $350 per tire, however, High-performance tires can cost anywhere between properly over $500.
Try not to go faster than about 15-20 miles per hour on a flat. Doing so may cause irreparable damage to the metal wheel beneath the tire, and could even cause you to lose control of the vehicle.
Flat tires aren’t always caused by a hole in the rubber. Instead, a malfunction or leak in the valve stem can be the culprit. The valve stem is the part of the tire that you unscrew when adding air. Any damage or even dirt on this small piece could cause your tire to lose air until it’s completely flat.
If you have not prepped your vehicle for a long time of not driving it you should not let it sit for more than one month, and even then, you should try to start it up and drive it for 15-30 minutes a few times within the month.
If you have standard passenger tires (ninety percent of vehicles do) the lowest tire pressure you can generally drive with is 20 pounds per square inch (PSI). Anything under 20 PSI is considered a flat tire and puts you at risk for a potentially devastating blowout.
Driving on a flat tire can cause internal structural damage to the tire, may lead to wheel and vehicle damage and may result in poor vehicle handling and control which could lead to an accident, injury or death.”
Make sure you drive no longer than 1.5 miles and go no faster than 20 mph – this is the only way to ensure that your tire has any hopes of surviving this disaster.
