Advice

Run-Flat Tires: Pros and Cons

By 08/21/2024 2:00pm
2020 Infiniti Q50 run flat tire

Quick Facts About Run-flat Tires

Run-flat tires. The name says it all — at least, that’s what you might think. There are pros and cons to these unique tires. Most importantly, they allow drivers to travel a short distance safely and comfortably following a puncture. 

Run-flat tires are common on certain cars you may be looking at buying. They are widely available at retail as replacement tires. But like most advanced safety devices, they cost more.

In this article, we’ll look at the advantages and drawbacks of run-flat tires, what they cost, and how they work.

What Are Run-Flat Tires?

Run-flat tires offer unique construction, giving them an ultra-stiff sidewall. The sidewall can support the vehicle’s weight at near-highway speeds, even without air in the tire.

What Makes Run-Flats Different from Standard Tires?

A standard tire will go flat when punctured. If driven for longer than it takes to pull off a road, it will almost immediately damage a wheel.

The big selling point of this product is that drivers who get a flat can drive a few miles, or maybe even more, to reach a safe place. Once safe, you can install a spare tire or replace the tire. Just how far you can drive on a run-flat tire without any air in it varies by manufacturer and tire type. Typically, they can be driven around 50 miles at about 50 mph.

Some automakers fit these tires as standard equipment on specific models. When it comes time to replace them — either due to worn tread, age, or damage — consumers are often faced with a choice: sticking with run-flats or switching to conventional tires.

RELATED: Car Tires Guide: Everything You Need to Know

Preference for Luxury and High Performance 

A wide variety of luxury automakers fit run-flat tires to cars at the factory. Most BMW and Mini models include them, and Mercedes-Benz sedans and SUVs also have them. Other luxury brands using them include Audi, Cadillac, Lexus, and Infiniti. Even certain Toyota Sienna minivans come outfitted with run-flats.

Higher-performance cars, such as the Chevrolet Camaro and Corvette, may include run-flat tires on certain upper trim levels.

Since tire companies make this type of tire in many sizes, some drivers choose to install them even on vehicles that don’t call for them when new. When in doubt, this message will be marked on the tire’s sidewall.

Electric Cars and Run-Flat Tires

Most electric vehicles do not house spare tires because the cars need space for EV batteries. As a result, several manufacturers make run-flat tires standard. Run-flat tires could also play a critical safety role for autonomous cars in the future and help keep people safe during a tire emergency.

How Do Run-Flat Tires Work?

Run-flat tires have been around for the better part of 40 years, though tread compounds did not become feasible for use in mainstream cars until the 2000s.

Two Design Styles

Run-flat tires feature one of two basic layouts that can keep the wheel itself well away from the ground in the event of a typical puncture or other air loss.

1. Self-Supporting Sidewall System
The most common is a self-supporting sidewall, which features reinforced construction of hard rubber that won’t collapse after a tire puncture. A variety of manufacturers make self-supporting run-flat tires. Their sidewalls can be several times beefier. While you can drive on them for short distances thanks to those thick sidewalls, they are not true “airless” tires. Such designs have been tested but not yet offered on regular-production vehicles.

2. Supporting Ring System
Less common is a supporting ring system. These tires employ a central ring of hardened rubber to support the vehicle in air-loss situations. Few mass-market vehicles include them, though certain heavy-duty or military-oriented cars may come with this tire type.

The Importance of Tire Pressure Monitoring Systems

Tire pressure monitoring systems (TPMS) are imperative when using run-flat tires. They display a warning about low tire pressure on a vehicle’s instrument cluster. The federal government began mandating TPMS on passenger cars in late 2007, and automakers either fit a basic warning system with a single light or offer more advanced systems displaying individual tire pressures.

RELATED: What Do the Numbers on a Tire Mean?

The Cost of Run-Flat Tires

Typically, designing for increased safety increases the cost of run-flats, but there are other reasons why they cost more than their standard counterparts.

Run-flats are less common than standard tires, which means fewer buying options. Additionally, most cars leave the factory with new standard tires. So, there is generally less demand for tires that can support themselves for short distances. One would be more likely to replace with similar types of tires.

Also, they use more rubber, which increases the tire manufacturer’s material cost.

Price Point Compared to Standard Tires

Depending on brand and vehicle, run-flats can cost as much as double what equivalent conventional tire costs. Still, you can find deals. For instance, Tire Rack currently charges between $217 and $270 for various Bridgestone run-flat tires that fit a 2016 BMW 328i. In comparison, the retailer lists different non-run-flat tires made by Bridgestone fitting that BMW for between $171 and $217.

Advantages

  • Convenience: Run-flat tires are all about convenience. While today’s tires are far less susceptible to punctures and other air-loss situations than those in years past, all it takes is a strip of metal or a long nail to ruin your day.
  • Safety: With these specialized tires, you may be able to continue to your destination or at least to a shop that can remove and replace the punctured tire. A driver needs to pull over immediately — perhaps even onto the side of a busy highway — if they have a conventional flat tire.
  • Rides well when flat: Because they maintain the primary “carcass,” or shape, of the tire, they mean relatively little handling and ride compromise after a puncture. A conventional tire will handle much differently — especially when punctured and the tread rubs against the metal of your wheel.
  • No spare tire: A vehicle built with run-flat tires when it was new won’t have a spare tire, reducing weight and increasing cargo space.

Drawbacks

  • High replacement cost: Drivers often think about the cost of replacement as one of the most significant downsides to run-flat tires. But the thick sidewalls that make them so good at their job have a significant impact on ride quality.
  • Stiffer ride: Run-flats ride stiffly, which may displease drivers looking for a plush cruise. Their unique tread patterns can also lead to shorter tire life and more necessary repairs.
  • Not 100% indestructible: Impact with a large or especially vicious piece of shrapnel may cause enough damage to render a run-flat unsafe to drive on, the same way a destructive event impacts a standard tire. And if that happens, the lack of a spare tire in a run-flat-equipped car means you’ll be calling a tow truck.
  • Not easy to replace: Replacing these wheels isn’t relatively as easy, either. Tire shops do not always stock them. So, drivers in smaller towns or rural areas may need to wait days for a replacement to arrive from a warehouse.

Can You Patch Run-Flats?

You cannot use a “plug” patch to fix a flat on these special tires. The unique rubber compounds used in their design do not allow for it. Most will display a “Do Not Repair” message directly on the sidewalls.

Additionally, a bulging sidewall — a tell-tale sign of a damaged conventional tire — may not be visible with a run-flat tire. The only way to determine if a significant impact compromises the tire’s structure with a pothole or curb is to remove the tire from the wheel and inspect it closely. This process alone can cost up to $75 and may take a shop the better part of an hour to complete since the wheel will need to be re-balanced afterward.