Here’s my (professional) take on run-flat tires to help you decide what’s right for your car.
What Are “Run Flat” Tires?
‘What are run-flat tires’ is one of the most commonly asked questions in tire shops.
The basic function of run-flats that makes them different from conventional tires is that you can drive on them for a limited distance at limited speeds (see specific manufacturer recommendations) in the event of tire deflation.
Want to avoid this?:
I think we all do…
So what makes run-flat tires different than standard tires?
A stiffer sidewall. Run-flat tires have extremely reinforced sidewalls.
I can instantly feel whether or not a tire has the run-flat ability when rolling a set out to my bay because the beading edge is extremely sharp.
Some automakers (like BMW, Cadillac, & Mini Cooper) make some new vehicles stock with original equipment run-flat tires and they aren’t even equipped with a spare.
There are two different types of run-flat tire construction:
- Self-supporting (Goodyear captive air tires)
Self-supporting run-flats have reinforced sidewall construction that supports the weight of the vehicle when the tire has a complete loss of air pressure. These are the most commonly-used run-flat tires on modern vehicles.
- Support ring system (Michelin PAX system)
The other run-flat design used less commonly these days is the PAX design by Michelin which requires the installation of a protective ring that lines the entire inside middle of the tire.
Are Run-Flat Tires Good To Have?
For most of you, I would advise leaving tire and wheel changes to the professionals. So yes, I do say that run-flat tires are good to have if you have the budget for them.
But of course, run-flats have their pros and cons. Here are a few:
Advantages Of Run-Flat Tires
Use your judgment to weigh out the ups and downs of using run flats. Some people love ‘em, some people loathe ‘em. Here are a few advantages:
- No more switching out to the spare
The gem of having run-flats on your car is that you don’t have to sit on the side of the highway with vehicles whizzing by. If your TPMS sensor tells you your tire is flat, you can simply lower your speed to no more than 50 MPH (90 kilometers per hour), and limp it on into your nearest tire shop.
If you do use a spare tire remember to re-inflate it to spec during every oil change.
- Less tire-changing accidents
Not gonna lie, there’s a lot that can go wrong when changing out a wheel on the side of the road, and using run flats eliminates a lot of hazards. For example, if you don’t chuck one of the wheels, the car can fall off the jack completely and bang up your brake rotors (the car can fall on top of you).
And there’s also the risk of not torquing the wheel bolts completely down when switching out to the spare (a very common mistake) causing the wheel to fly off while driving.
The opposite mistake of torquing the wheel down too hard makes some ‘fun’ extra work for the tire technician to drill out the broken-off wheel bolt (plus the extra cost).
In terms of my significant other, I’d much rather she used run-flat tires to avoid getting stranded while driving. She’s fully capable of changing out a wheel, but I’d rather not have to stress about it.
- Safer tire blowouts
Because the sidewall is significantly stiffer on run-flat tires, there’s a much smaller chance of the tire coming completely off of the wheel in the event of a tire blowout. Consequently, you likely won’t be included in the statistics of the thousands of yearly tire-related accidents that occur in the USA each year.
Not getting stranded is awesome, and long road trips can sometimes result in disaster when a tire goes flat, so I do commend run-flats for being a saving grace for some drivers (remember to bring lots of water).
- Avoid awkward rides with tow truck drivers
We’re all grateful for those hard-working, sweaty tow truck dudes for bailing us out of a mess. But sitting in their spring-loaded passenger seat filled with already-spit sunflower seeds and multiple empty Pepsi cans isn’t that cool. I’ll pass on that.
- Higher speed rating
Run-flats can typically be driven faster than traditional tires since they’re made of stiffer rubber (they’re made for high-end vehicles anyway).
- Sketchy neighborhood rated
Why not, I’ll bring it up. Do you live in a sketchy area where someone could potentially try and shoot out your tires? Not this time! Out chase the robbers with run flats every time, no prob. It’s Murphy’s law. I’ve met customers who spend hundreds of thousands to bulletproof their entire G-Wagon for no good reason, and of course, they use run-flat tires.
And yes, when your ex-lover gets mad and slashes your run-flats you can just drive them to the store for another set. No sweat!
Disadvantages Of Run-Flat Tires
There are plenty of downsides to using run-flats. Here are a few:
- Potential for breaking the TPMS (tire pressure monitoring system) sensor
Whether you have regular tires or run-flat, there’s always the risk of damaging the TPMS sensor when driving on a flat tire. And you’re not going to be happy to pay an additional $100-$200 for a tire pressure sensor after your tire blows out, trust me.
And if you drive too fast on your run-flats when they’re flat, that’s just what’ll happen.
- Extra price
Expect to pay at least $50 USD more for tires with run-flat technology. Tire technology costs money to engineer, therefore the product will always be more expensive for the consumer. I pass at the idea of spending $200-$300 for each tire when other economical models get the job done just fine.
- Harder to mount
From a technician’s point of view, run-flats can be a huge pain in the ass to mount. The rubber is stiff, and run-flats usually have ultra low-profile sidewalls. Sometimes I feel like I’m going to run out of tire lube, and I almost always have to switch out my nitrile gloves after mounting these up.
It’s like trying to replace a garbage bag that’s too small for the bin (but requires much more force).
- Bumpier ride quality
Because of the stiff sidewalls on run-flat tires, you feel every little bump on the road. I’d much rather be running a conventional Continental or even a quality inexpensive Altimax RT43 compared to any run-flat. The solution is to keep a tire patch kit and portable air compressor in the vehicle at all times.
- Run-flats weigh more (reduced fuel economy)
I’ve noticed that the heavier rubber makes these bad boys harder to lift and install onto the wheels, so they’re going to slightly reduce your fuel economy.
- Vehicles with stock run-flats don’t have a spare
One thing I’ve noticed when changing the oil on luxury cars is that when I go digging to reinflate the spare tire… I can’t find it?? That’s because car manufacturers BMWs, Mercedes, and Mini Coopers don’t always make space for a spare tire, and that could cause problems in the event of a catastrophic tire failure.
- Lower mileage guarantee (if there is one)
One thing you’ll notice with run-flat tires is that they skimp you on the treadwear warranty. WTF is up with that? You spend 50% more for the tire to end up being out of luck when the tire is punctured?
See Scotty Kilmer’s video on ‘Why Not To Buy Run Flat Tires For Your Car’. The dude is hilarious, and he does have a point.
Do Run Flat Tires Work?
Absolutely yes. In fact, on performance cars with low-profile sidewalls (like Mercedes AMG), I sometimes can’t even tell if the tire is flat when it comes into the shop for repair.
These are a must-have for highway luxury vehicles because they’ll hold up when you’re doing 130 MPH on I-15 on the way to Vegas in 120-degree heat. Just saying.
How To Identify A Run Flat Tire?
To complicate things a bit, each tire company has its label for run-flat tires. Some are easier than others to identify.
For example, Continental prints an SSR (self-supporting run-flat) on their tires’ sidewalls, Michelin prints ZP (zero pressure), Pirelli prints RSC (reinforced sidewall construction) or Run-Flat, Bridgestone labels RFT (run-flat tire), and that’s just to name a few of the top brands.
I recommend whipping out your cellular and running a quick Google search specific to your tire brand if you’re not sure.
Check out this guy who intentionally punctured his run-flat tire to inspect the results:
Run-Flat Vs. Regular Tires
Let’s quickly compare run flats to the normal (and perfectly good) tire. Run-flats cost a bit more, typically have a lower sidewall design (mostly because they’re used on sports cars), have stiffer rubber, and are heavier.
On the contrary, regular tires have a higher sidewall that provides a bit more natural suspension and a comfier ride, blow out easier when they go flat, have a longer mileage warranty, are cheaper, etc.
The most important point to note about using regular tires is that the repair shop will put a plug in it if it’s punctured. Think of it as a tax for the rich by the business owner. They’re never going to want to try and repair a run-flat tire.
Run-Flat Vs. Self-Sealing Tires
Are run-flats the same as self-sealing tires? No. Self-sealing tires excrete a sealant in an attempt to seal the hole after a tire puncture whereas run-flats simply support the vehicle’s weight and can operate at slow speeds when completely deflated.
Can You Plug A Run Flat Tire?
Most repair shops will recommend a complete replacement tire (or two tires if your car is AWD), and they’ll also refuse to put a plug in your run-flat tire for ‘insurance reasons’. Plus, they just want to sell you a new tire, come on, it’s a business.
And yes, some run-flat tires indeed have such stiff rubber that the plugs still leak a bit.
Quite honestly, after years of just replacing run flats at the shop, I decided to try and save my mom some money by performing a tire repair on her BMW X3 run flats. And guess what? It worked just fine.
But like any tire, don’t try to use a plug if the puncture is an inch or two from the sidewall. It’s not going to work. Just replace it with a new tire.
Final Thoughts On “Run Flat” Tires
Would I use run-flat tires on my vehicle? As a professional auto technician, no. I just pull out my Milwaukee 1/2-inch impact and rip the tire off in 2 seconds flat when I need to change out to the spare. I also keep a tire repair kit and portable air compressor inside my truck at all times just in case.
But run-flats do have their place, and if I had a sports car with an unlimited budget I’d probably have some Pirelli or Continentals fully equipped—I’d let the tire store do all the work.