The Pros and Cons of Run-Flat Tires

There Are Trade-Offs to Convenience


  • Run-flats for BMW

    Run-flats for BMW

    Nearly every BMW vehicle comes standard with run-flat tires. | July 31, 2014

3 Photos

A flat tire often happens at the most inopportune moment or location. 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 and you don't 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 time, providing the driver with roughly 100 miles of range to find a repair shop. While it may sound like the perfect solution, car owners and car shoppers should know about the trade-offs.

Run-flat tires are standard on 12 percent of new vehicles, according to Edmunds data. Traditionally, carmakers have used run-flat tires on sports cars, but in recent years they have started to use them for other cars, too. Cadillac and BMW, for example, have made run-flat tires standard on a number of their sedans.

Self-Supporting Tire
The most common type of run-flat tire in use today is the self-supporting tire. The tire's sidewalls are heavily reinforced to support the vehicle when the air pressure is low or even when the tire has lost all its pressure.

Pros:

  • You can drive on a flat tire: The primary benefit of a run-flat tire is that it allows you to keep driving about 100 miles after all the air has gone. This means that a person doesn't have to get out of the car in the cold, or the rain, or onto a busy highway or on the street in a sketchy part of town. Drivers will usually have to reduce speed to about 50 mph to get the maximum range. The owner's manual will have exact figures for each tire/vehicle application.
  • Better stability after a blowout: Because this tire can support the vehicle without air, a sudden deflation results in less weight transfer and tread destabilization. Steering and handling will remain near normal.
  • Lower vehicle weight: With the spare and tire repair tools eliminated, vehicle weight should theoretically go down. But it's not as much as you might expect, since run-flat tires weigh more than regular tires, due to the added sidewall reinforcement.

Cons:

  • No spare: Vehicles equipped with run-flat tires carry no spare, which means they don't have the jack or tools either. In fact, eliminating the spare and reallocating that space to some other purpose (styling, third-row seat, interior room, etc.) is a big reason why carmakers offer run-flats.
  • Reduced tread wear: A recent study by J.D. Power found that people were replacing their run-flat tires an average of 6,000 miles sooner than owners using standard tires. Opinions differ on why this is, but one theory is that tiremakers put a soft tread compound on a run-flat tire to counter the hard ride. A side effect of the softer compound is a shorter tread life.
  • Blowouts are still possible: If a driver fails to heed or notice the run-flat warning and drives beyond the zero-pressure range or above the speed limitation, the tire can begin to disintegrate, with the same destabilizing effects. Additionally, if the puncture occurred on the sidewall or if the tire hits a large object, the driver would have to call a tow truck. The J.D. Power study found that "customers with vehicles equipped with run-flat tires are nearly twice as likely as those with vehicles equipped with standard tires to have to replace a tire due to a flat or blowout."
  • Hard to tell if it is low on air: A side effect of the stiffer construction is that the sidewalls do not bulge if the air pressure is low. This means that it is critical to have a tire-pressure monitoring system and check your tire pressure frequently.
  • Harsher ride: The stiff sidewalls that make a run-flat work also result in a harder ride. If the vehicle came with run-flat tires from the factory, the automaker usually tunes the suspension to offset the harsher ride.
  • Cost: Run-flat tires are more expensive to replace. A 205/55R16 run-flat tire at a local shop in Santa Monica, California, costs $239. The standard tire equivalent costs about $174, a $65 difference per tire. Also, many run-flat tires cannot be repaired and often need to be replaced in pairs.
  • Less on-shelf availability: Because run-flats aren't a big-selling tire, drivers shouldn't expect to roll into just any tire store and buy one. It may be easier to do so in larger cities, but if you're a run-flat user on a road trip and get a flat near a small town, you'll probably have to make a detour to find a suitable tire dealer. Or worse, you may have to stay there overnight, waiting for the tire to be shipped.

Self-Sealing Tire
The 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 not larger than 5mm and is near the center of the tread.

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 and lower availability.

This type of tire isn't standard on new vehicles, but is worth mentioning since it is available as a replacement tire. Continental and Pirelli are two tiremakers that produce self-sealing tires.

Make an Informed Purchase
Run-flat tires seem to have more downsides than upsides, but many people swear by them. Take the time to read customer reviews and know what tires come standard on a car before making your decision.

Comments

  • kawzx7 kawzx7 Posts:

    Runflats are pretty awesome. Just put my second set in. Continental makes the best runflat as far as I'm concerned.

  • traveltons traveltons Posts:

    Run flats bring piece of mind as long as you don't travel more than 50 miles from a tire shop that carries your tire size.

  • when you read the pros and cons in this article, it would make you wonder what percentage of people would choose to renew their run-flats once they wear out and why. For me, the run flat tire is the answer to the question that nobody asked.

  • isellhondas isellhondas Posts:

    I really think Honda got sold a bill of goods in 2005 when they started putting Michelin PAX run flats on their Touring Odysseys. All stores had to spend something like 5000.00 to buy a special machine that could change them. Customers complained that they wore out quickly and they were VERY expensive to replace since they really had no competition. I think you could drive 150 miles on a "flat". That would be of no value if you were in the middle of Montana with the nearest Honda Dealer 200 miles from you. Very few tire stores would buy the necessary equipment or stock these tires. I could be dead wrong but I think Honda thought they would be the leader in a new technology that would be accepted and become the wave of the future. They were dead wrong in this thinking. Most Tourings have been converted to conventional wheels and tires I would think by now. I agree. an answer to a question nobody asked.

  • There are rumors of a new tire technology which is basically a solid tire that is somehow spring ?? loaded? Maybe that'll work. But look, if you run on a run flat long enough, you're going to run it anyway and it'll cost 2X as much as the regular tire you ruined by running it to the shoulder of the road. If you HAVE to get off the road, you can run on the dang rim if you have to get 50 feet one way or the other. As soon as my run flats got worn out (all too quickly I might add) I ditched 'em. Blow outs? flats? Not in the last 5 years. I sorta group run flats along with under-your-seat hammers to break the glass in case your car is submerged. Only they cost $800 instead of $15.

  • zackai zackai Posts:

    I had my front tire replaced recently. The problem was that it got a screw in it. I didn't notice much abnormal things except the car complains that tire air pressure is low (not much noticeable externally) twice within two months (during then I still drove 80 miles/h on highway), which I feel quite impressive. But also, I was told that they couldn't patch a run-flat tire and alway need a replacement in such a case.

  • thecardoc3 thecardoc3 Posts:

    That is correct, run flat tires cannot be repaired. It is impossible to be certain whether or not the tire has sustained internal damage while it was being driven on under inflated. Since the shop would be legally responsible for the drivers safety if they repair the tire the only logical choice is to replace the tire.

  • Bridgestone says you can repair their run flats under certain conditions but they don't necessarily recommend it (that's the lawyers talking). "Certain conditions" mean puncture of less than 6mm for both side-reinforced type and support-ring type Run-Flat Technology tires, plus minimal damage to the support ring in case of the latter. How you determine that is a big question. However, you don't even need a puncture to scrap a run-flat tire. If you drive on one in an underinflated or no inflation condition, even IF driven within their speed and distance limitations, this can permanently damage their internal structure, surrendering strength and durability. Seems to me for the price of a tow truck or AAA card, you can tow your car with regular tires to a repair shop and fix that tire for less money than replacing a run-flat after having run on it to get to a repair shop.

  • kyfdx kyfdx Posts:

    The problem with most models that come with run-flat models, standard... is there is no place to put a spare tire. So, even if you switch to normal tires, you don't have a spare. You can get towed wherever you want, and sit and wait for them to send in that 255/35-18 tire you need.. (whether you have runflats or not) So, my issue isn't with the cost.. it's the lack of a spare.

  • I've been running 5 years without a spare. The one time I had picked up a large screw in those 50,000 miles, I just filled the tire with the electric air pump and motored 3 miles to the tire shop. For that slight inconvenience I saved 50,000 miles of hard riding, noisy tires---oh, wait, my RFTs wore out in 20,000 miles, I forgot. It's my opinion that RFTs were developed solely to allow auto engineers to create more space without a spare tire; so in essence, the RFT is sold to save THEM money, and cost you more in operating costs, all for the dubious immunization to disaster which never seems to happen to 99% of the people who run RFTs. The only disaster is paying for new ones. Every flat tire with an RFT is a $200 flat. Sure if I were commuting in Iraq I might like them.

  • zackai zackai Posts:

    The problem with most models that come with run-flat models, standard... is there is no place to put a spare tire. So, even if you switch to normal tires, you don't have a spare. You can get towed wherever you want, and sit and wait for them to send in that 255/35-18 tire you need.. (whether you have runflats or not) So, my issue isn't with the cost.. it's the lack of a spare.
    I remember that in the old days most cars had a spare tire even for those with small trunk. I guess back in those days there weren't so many tow trucks, nor repair shops. My recent search for old Japanese performance car also notice that. Some still come with (stock or not) a spare tire in the tiny trunk.

  • stever stever Posts:

    I've had two flats since June on my van. It has a spare hanging underneath and I had to use it for one of the flats. Spotted the other one in time to go 8 miles into a town (thank you TPMS). Sure is nice having a spare on the gravel backroads we like to cruise, where cell coverage is spotty, much less mechanics.

  • Well that's an extreme situation. Not too many BMWs on gravel backroads in the desert. And for those few intrepid luxury car drivers, I'd recommend getting a BMW spare tire kit. If you can avoid running flat for very long on your "run flats" you can save yourself the price of the spare tire kit the first time you remove the flat-run-flat before ruining it completely. This RFT technology reminds me of this new fighter plane the Germans developed in WW II. It was so slow and clumsy however, that they had to send a real fighter plane to protect each "new" fighter plane they sent up.

  • stever stever Posts:

    Yeah, but my first flat happened 5 minutes after picking up a nail in a McDonalds parking lot. The tire went down so fast the TPMS didn't help. I should have just called for a tow on that one since I was still near the small town and the tow probably would have been fast. Most places you have to cool your heels for an hour or more waiting for the tow truck. I can change a flat in 15 minutes.

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