There is no good time for a flat tire. In addition to the danger of a blowout, there is the hassle and cost of being stranded until the tire is replaced. To improve safety and ease the difficulties posed by surprise flats, run flat tires were invented. Although run flats are only standard from a select few manufacturers, you can have them installed on any car. Just make sure you know what you’re signing up for before making the swap.
How They Work
Run flat tires have two basic designs: a sturdy sidewall construction (self-supporting) or a stiff inner ring (auxiliary supported). With regular flats, drivers must pull over immediately, because the weight of the vehicle on the wheel rims can cause serious, costly damage and create unsafe driving conditions with unpredictable steering. Run flats are designed to keep you safely on the road longer in the event of a loss of air pressure. Self-supporting run flat tires rely on strong reinforced sidewalls to support the weight of the vehicle in the event of a puncture or loss of air pressure. The sides of the tire are thick enough to carry the vehicle additional miles without damaging the wheels or suspension system. Auxiliary-supported run flats have a tough and rigid ring around the inside of the tire, hugging the wheel. When these tires lose air pressure, it’s this ring that contacts the road, not your rims, and allows your wheels to keep spinning.
The Good News
Sounds pretty good, right? Run flats can add 50–100 miles after losing air pressure, which gives you time to drive home or to a local NAPA AutoCare to remedy the problem. They also offer increased safety in case of a puncture. They provide a smoother ride on what would otherwise be a flat tire, leaving you in control of the vehicle and saving your car from costly repairs. In fact, sometimes they work so well that you can’t even tell you have tire damage. Therefore, it’s extra important (and, in fact, government mandated) that your tire pressure monitoring system (TPMS) is in top-notch condition to warn you of any problems. Run flats also mean you don’t have to wait by the side of the road for a tow truck, which is always a plus.
The Bad News
Despite the added security and potential cost savings in terms of damage, run flats remain the exception in the tire market. They have some serious drawbacks that have prevented them from becoming the norm, which must be taken into account before you make a purchase decision. Due to their rigidity, they provide a bumpier ride than standard tires. They also wear faster, must be replaced more often at a higher price, and, because they don’t absorb impacts as well, are less fuel efficient. Ironically, run flats have been reported to sustain damage more often, due to their stiffer, less forgiving nature.
Ultimately, you must weigh your priorities against these factors and make the decision for yourself. Always read manufacturer-provided materials, as the available distances of run flat tires vary. It’s also important to note that run flats can’t always be driven when damaged. Sidewall-damaged self-supporting tires cannot be driven at all, for instance. If the puncture is near the middle of the treads, follow instructions regarding mph, distance, and any other information included by the manufacturer.
For more information on run flat tires, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.
Photo courtesy of Flickr.
Blair Lampe is a New York-based professional mechanic, blogger, theater technician, and speechwriter. In her downtime she enjoys backpacking wherever her boots will carry her, rock climbing, experimental theatre, a crisp rosé , and showering love on her 2001 Sierra truck.