Run-flat tires are just what the description implies, but also a little less than that.
Depending on the manufacturer, they may have designations such as RFT (run-flat tire), ROF (run-on-flat) or ESP (extended service protocol). In general, run flats are tires that will continue to run even after pressure is lost. They are usually engineered to travel safely at up to 50 miles per hour for up to 50 miles without incurring additional damage. They are not intended to run indefinitely without proper inflation. Your tire pressure monitoring system would tell you when pressure is lost.
Run-flats are beneficial in many situations:
- If your car isn’t designed to hold even a temporary spare — some sports cars, for instance — you won’t be without protection if you get a flat.
- You won’t get stuck on the side of a busy highway or road that lacks shoulders if you get a flat tire.
- If you’re on the way to an appointment or have children in the car, you won’t have to wait for a tow.
- Because run-flats can reach and maintain a speed of 50 mph after pressure is lost, you won’t be driving at a dangerously slow speed in highway traffic.
- In many cases, 50 miles gets you safely to a repair shop or home.
There are, however, some important things to know about run-flats:
Run-flats cost more. The run-flat version of a tire will cost more than a conventional tire in the same line because run-flats are more expensive to manufacture.
They are a temporary solution if pressure is lost. You must have a run-flat tire repaired or replaced within 50 miles of use after one of these tires goes flat.
You may sacrifice ride quality. Run-flat tires have stronger sidewalls than conventional tires do, enabling run-flats to function without being inflated. But stiffer sidewalls also mean less flex over bumps or potholes so your ride may not be as smooth even when the tires are properly inflated.
Some run-flats cannot be used on all vehicles. Most run-flat lines are intended only for vehicles that had run-flats as original equipment. A few can be used universally, as long as they meet load, speed and size requirements. Ask a tire expert which lines are appropriate.
Run-flats and conventional tires should not be mixed. The difference in handling characteristics makes it dangerous to have conventional tires and run-flats on the same car. It’s also not advisable to mix different brands or models of run-flats.
Replacements may be hard to find. Sometimes run-flats are made for just one car, and succeeding models of the same tire handle and perform differently from the originals. Shopping for a good used example that matches your other tires — tires you might find at BestUsedTires.com — could prevent you from having to buy four new tires when only one is damaged. That could save you well over $1,000.
If you have a car that was equipped originally with run-flats that are no longer made, talk to a qualified tire expert before buying replacements. He’ll make sure you get tires with similar handling and performance characteristics.