Happy Meals. Kitchen Appliances. Water guns. And iTunes. Four things that somehow keep getting worse with “improvements.” When it comes to tires, many might put run-flat tires into that category as well. After all, you would naturally think that a run-flat tire was a cutting-edge innovation from the tire industry. “A tire that won’t go flat and won’t leave me stranded on the side of the road? Sounds too good to be true!”
But if run-flat tires are so innovative, why aren’t they more prevalent? Are run-flat tires any good? How long do run-flat tires last? And how do they stack up against regular, traditional tires?
Let’s take a look at each of those questions.
Run-flat Tires vs. Regular Tires
The difference between run-flat tires and regular tires comes down to their construction. Whereas regular tires are made entirely from a rubber compound, run-flat tires have reinforced sidewalls which allow them to shoulder the weight of your vehicle and support its continued momentum for a limited amount of time and distance. This is welcomed news for any driver that’s ever heard the infamous “pop” or “thud” sound that comes from driving on a flat tire.
The technology in run-flat tires allows you to continue on your journey and deal with replacing the tire later, rather than being sidelined on the side of the road waiting for a repair truck or tow truck. Most run-flat tires are rated to carry vehicles a distance of 50 miles at a speed of 50 mph. Interestingly, this is the same rating for most compact spares (also called donuts), though run-flat tires come with the added convenience of not trying to use a jack and wrench on the side of a highway or backroad on a rainy day.
We’d be remiss if we didn’t point out that there are actually two different types of run-flat tires: “self-supporting” tires, which have reinforced steel sidewalls and generally are the most common; and “support ring” tires, which have a hardened piece of rubber around the wheel. Both types provide the same service: enough support to keep the vehicle going for approximately 50 miles after losing air pressure.
But how well do run-flat tires ride compared to regular tires?
Jake Lingeman at Autoweek wrote a very fair and balanced article in 2019 title “Why do Run-Flat Tires Suck? Science, and Tradeoffs.” Obviously that’s a joke, though Jake most certainly is not: he’s a veteran automotive journalist who’s been with Autoweek since 2006. We’re regular readers of his content and have learned a ton from him.
Back to run-flat tires. In the story, Jake interviewed Woody Rogers from Tirerack.com who offered this explanation:
“It’s the air inside a tire that carries the load. Even when properly inflated, the reinforced sidewall structure [in a run-flat tire] is stiffer than the sidewall of a conventional tire. The added spring rate of that stiffer sidewall can be felt over every bump.”
In short, most drivers report a far stiffer ride in vehicles equipped with run-flat tires. If you’re in a performance automobile you likely won’t mind the added stiffness. But if you’re transporting your family, expect at least someone (likely the loudest, most opiniated person you know and love) to comment on the ride.
Are they more expensive?
Although estimates vary quite dramatically from a few cents to upwards of $50 more per tire, run-flat tires generally are more expensive than regular tires. Typically this cost is largely hidden when purchasing a new or used vehicle that already has these types of tires equipped. But drivers can certainly expect to see the added costs when adding or replacing run-flat tires on their current vehicles.
A different source claims that run-flat tires also do not last as long as regular tires, estimating that they wear out on average 6,000 miles faster than regular tires. We chose not to include a citation or source here because there were a lot of caveats with this calculation, not least of which was a call out stating that this phenomenon may occur because most run-flat tires are not repairable (more on that below). But in the interest of full disclosure and our mission to provide you with information sourced from across the internet, we wanted to share this with you. Know that we will continue to investigate this claim and update this article accordingly as more information becomes available.
And are they harder to find?
Most major tire manufacturers produce run-flat tires. Bridgestone has an entire lineup called DriveGuard. The catch, however, is that manufacturers do not produce them in every type and size tire as they do regular tires, certainly not in the quantities that they make regular tires. This means that retrofitting your vehicle with run-flat tires may prove difficult if not impossible, and replacing one on a vehicle that already has them can be more cumbersome than replacing a regular tire on account of having to find the exact right fit.
Can I replace my run-flat tires with regular tires?
This is a classic answer: “Yes, but…”. The reality is that you can put any tire on your vehicle so long as the size is right for your vehicle and matches the other tires.
In the case of run-flat tires, since they are known to ride a bit stiffer than traditional tires many vehicle manufacturers compensate by specially tuning their suspensions to account for the stiffer ride. This is good news to car buyers purchasing vehicles that come with run-flat tires, but bad news to those same buyers when it comes time to replace an aging or damaged tire.
Why?
Mixing and matching run-flat tires with regular tires is a big no-no as it can severely throw off the suspension calibrations on your vehicle, especially if those suspensions have already been tuned to accommodate run-flat tires. So be warned: if you start with run-flat tires, you may be committing to them for the life of your vehicle.
Then there’s the issue of repair. Some manufacturers – we’ve heard Pirelli is one of them – explicitly state that run-flat tires should never be repaired, only replaced. Regular tires with punctures on the tread (as opposed to the sidewall) can be repaired with a patch kit (old timers like us used to call them plugs… some repair shops still do). These kits/plugs cost $30, a far cry from the $200+ that a new run-flat can easily cost.
Recapping the Pros and Cons
So, as with so many other elements in life, there is no clear cut answer and the choice is ultimately yours. Yes, run-flat tires offer some advantages over regular tires, but there are compromises to make for those advantages and, for many, they simply may not be worth it.
As self-described old timers (we’re not that old – just two dads in our 40’s with an unusual passion for tires), our goal with most of our reporting is not to offer an opinion but, instead, invest time researching and sharing the most reliable information with you in aggregate. Our hope is that this will allow you to make the most informed decision for you and your family.
In the case of run-flat tires we’re willing to weigh in after one of us had a personal experience with them a decade ago. The ride was stiffer, that was for sure. I didn’t have a family at the time and was more invested in attracting members of the opposite sex, so I didn’t receive any “comfort” complaints from our passengers. On two occasions I lost a tire while on the highway. The vehicle’s sensor tipped me off to a drop in air pressure, which was the only way I knew a tire had deflated. Yes, there was convenience in being able to drive to a replacement shop, even though I had to drive with my hazard lights on going 50 mph instead of the posted 70 mph. And even at 50 mph, the car did not feel very happy, so I dropped it to 40 mph, earning lots of angry glances from the cars whizzing by me on the highway.
The breaking point for me was when I asked the local shop for a replacement. Because of low inventory, the best the repair shop could do was to have a replacement delivered in three days. With no donut/spare, I had no other alternative. So three days without a car; three days of calling out from work; and three days of being stranded at home. I even had to get a ride home from the shop owner.
Yes, all of this was before uber and zipcar, and certainly before “fast free shipping” on almost anything. But I knew then and there that run-flats would not be in my future, and I’ve avoided them ever since.