Run-flat tires may be new to you, but they are not a new technology to automotive applications. The first uses of run-flat tires occurred in the 1930s, with increasing prominence in the last decade on vehicles available today.
Due to the reinforced side wall design, a run-flat tire can support the weight of the vehicle after losing all air pressure, allowing for reasonably safe travel in order to get to a service center.
Is the benefits from a run-flat tire worth the price? I explore the benefits of run-flat technology and include some reasons against use you may not have considered.
What are Run-Flat Tires?
Run-flat tires have reinforcement designed to carry the weight of the vehicle for a short time when the air pressure is lost.
However, these tires were not designed to allow you to drive on any air pressure indefinitely – many have a rating of 50 miles, at a maximum of 50 miles per hour or less.
Regular tires are not designed to carry the weight of the vehicle without having any air pressure in them. The air pressure itself is the supportive factor of the tire. If you drive a regular tire without the right air pressure, the heat buildup will destroy the tire.
How Do Run Flat Tires Work?
Run-flat tires come in two primary types: the self-supporting system and the support ring system.
In self-supporting run-flat systems, the tire has reinforced sidewall construction that enables the tire to support the vehicle even after air loss. This design allows continued use after the air becomes depressurized up to the manufacturer’s specified speed and distance.
In support ring run-flat tire systems, a ring of hard rubber or other such structure is used to support the weight of the vehicle in the case of an air loss.
Since most run-flat tires will still perform when “flat,” all run-flat tires must to be placed on a vehicle equipped with a Tire Pressure Monitoring System (TPMS). The tire pressure monitoring system will tell you immediately if one of your tires loses pressure. Without the TPMS, you’d have no way of knowing you were driving with an underinflated tire.
If you do have a flat tire, there is no consensus on whether or not run-flat tires should be repaired. Tire manufacturers typically warn consumers to look to the vehicle manufacturer’s replacement tire recommendations and restrictions.
For instance, Michelin North America Inc. deems it acceptable to repair its run-flat tires (Zero Pressure) under some guidelines. However, the owner’s manual for BMW states that you cannot repair their original equipment run-flat tires.
Types of Run-Flat Tires
#1. Self-Supporting Run Flat Tire.
The most common run flat tire configuration is self-supporting construction. This tire does exactly what the name indicates.
When air pressure is lost in the tire, the sidewall construction can carry the vehicle’s weight. However, as the tire deflects, it can only do so for a limited distance/ time.
#2. Support Ring System Tire.
A support ring system does not use a sidewall reinforcement for a run flat tire. Instead, this run-flat tire construction contains a physical structure that gets attached to the wheel itself.
In this construction, the wheel, in a run-flat mode of operation, supports the vehicle weight. Again, these tires will also only last so long without the proper air pressure in the tire system.
Pros of Run-Flat Tires
#1. Allows You to Drive Without Air Pressure.
The biggest advantage of a run-flat tire is that you can keep driving after losing air. Instead of having to change it at night or in the rain, you can drive to a safer place to get the tire repaired or replaced along the road.
You will want to check your owner’s manual and determine how long you can run on the tire and the safest speed. Some tires will get you 50 miles and others to 100 miles.
#2. Stability Following a Blowout.
A standard tire going flat creates a handling and steering issue immediately. This is a concern for an accident or vehicle rollover potential.
However, this is not the case with a run-flat tire. The tires hold the weight of your vehicle which means the ride does not change very much. You will be able to safely drive yourself to your nearby tire retailer for assistance.
#3. Lowers Vehicle Weight.
You eliminate some overall vehicle weight without a spare tire or tools as well, but the amount isn’t terribly substantial because again the run-flats do have a little extra weight with the additional support.
Anyway, if you’re a sports car or convertible person, it can definitely be an advantage to not have to carry a spare. You can use the little space you have left over for groceries or a suitcase- pending weather, of course.
Cons of Run-Flat Tires
#1. No Spare Tire.
If you have run-flat tires, you won’t need a spare tire and you will not have the tools on board to change the tire.
While this frees up space to potentially do another thing, such as include a third row or more interior cargo space, that becomes an issue should you need a spare tire.
Run-flats are not fool-proof, and eventually you will find yourself in some sort of situation that will necessitate tire changing tools or a spare tire and you will not have it or ability to change it.
#2. Tread Doesn’t Last as Long.
Run-flat tires typically have quicker tread wear then most conventional tires, some suggest in that a soft tread compound is placed on the sidewalls of the run-flats to offset ride harshness.
Though they may need to be replaced sooner, there does not seem to be a high complaint level with run-flats. Many reports of customer satisfaction suggest it is nearly equal to a customer with conventional tires.
#3. Blowouts Can Happen.
Although it’s not very probable, the run-flat tires can still fail. If you ignore the warning or continue driving the tires past their limitations, the tire itself can disintegrate and this would then create the same destabilization to the motorcycle and rider as if you had a flat tire.
The sidewall could also be punctured by debris. In this scenario, you would now have to safely pull over and call a tow truck, as you do not have a spare tire on board.
#4. Hard to Diagnose.
When you drive on a standard tire, as air pressure is lost, the whole ride changes. With this change and modern tire pressure monitoring systems, it is easy to know when one of your tires is flat so you can address the issue prior to becoming stuck.
However, the sidewalls on a run-flat do not change when the air pressure is lost. These tires provide you with a stiffer construction and, therefore, you have to rely on the tire pressure monitoring system when an air pressure issue develops.
If the tire pressure monitoring system malfunctions and you are not checking the air pressures, you may be unaware that a problem exists.
#5. Harsher Ride.
Run-flat tires have a stiffer sidewall, which makes for a rougher ride. If you add run-flats to a car that was not originally made with them, you’ll feel it.
Buying a new vehicle equipped from the factory with run-flats does not usually pose much of a problem. The manufacturer will often have tuned the suspension to compensate for the stiffer ride and provide a little more comfort.
#6. Higher Cost.
The run-flat tire will cost you more in two ways. The tires themselves cost more to begin with–generally from about $35 to $75 more per tire.
Also, the run-flat is going to be less likely to have a tire repair done once something goes wrong.
The regular tire you would spend $25 to patch might need to be replaced by a run-flat, further increasing costs. And remember you have to replace your tires in pairs, so you aren’t just looking at the cost of one tire, but two.
#7. Fewer Available.
Run-flat tires are not as popular as traditional tires, so you may have more difficulty locating a set on the shelf.
If you’re in a large city, you’re more likely to locate run-flats. If you’re not in a large city, you will want to pre-order a set of tires before your appointment. If you need tires installed right away, you could wait a few days for them to arrive.
Run-flat Tire Costs
Regular run-flat tires are at least $150 to $500 for a passenger vehicle-35% to 200% over a regular tire. You may pay more if you drive a heavy-duty vehicle or luxury model.
Considering they usually should be replaced in pairs, expect to pay from $300 to 1,000 per set. If you need to replace all four tires, the total cost may range from $600 to 2,000 to replace with run-flat tires, which does not include installation and alignment.
How long do run-flat tires last?
Assuming your tire is not flat, a run-flat tire will last as long as a regular tire. But if your run-flat tire becomes punctured, it can last up to 50 miles before you have to service it; enough to get you to a tire repair facility.
Are run-flats worth it?
To see if a run-flat tire will be worth it or not, there are a few factors you should analyze first. For example, do you frequently drive on poor-quality pavement with a high likelihood of a puncture event?
If so, then it could be worth the price of admission as it prevents you from being stranded with a flat tire. Generally speaking, a run-flat tire will not strand you on the side of the road, in most cases. They work, but they are not perfect – yet.
How fast can you drive on run-flat tires?
Most run-flat tire manufacturers suggest you should not exceed 55 mph, but sometimes, one tire manufacturer may have different recommendations.
Therefore, it’s best to refer to the documentation from the manufacturer you purchased the run-flat tires from originally. Once the run-flat tire is driven over the manufacturer-recommended limit, it may not be safe to drive on – ever.
Are run-flat tires noisy?
Because the side walls on run-flat tires are thicker than a conventional tire, there will be slightly louder road noise. You may also feel that your car has a bigger bump than would be felt on a rough or uneven road, but test drive a car with run-flat tires before deciding!