Your Complete Guide to Run-Flat Tires From Zeck Ford
Tired of Flat Tires?
It’s a nightmare when you find that you are late for work because you had a flat tire. Or that the appointment you scheduled a month ago has to be rescheduled, due to a flat tire. Or how about that a job interview where you blew the interview because your tires blew. We’re sure you are easily tired of flat tires and all the headaches and inconveniences that ensue.
Tires, from their first inception, have always been extremely important when it comes to a vehicle’s safety and comfort. That being the case, tires are that part of a vehicle that experience the most bumps and bruises, literally, and figuratively. Be it exposure to rough elements, debris on the roads, or even extreme weather temperatures, tires take the greatest amount of beating.
Introducing Run-Flat Tires
Tire manufacturers are answering the call of duty. They have performed extensive research to improve a tires longevity and durability. They have recently developed tires that temporarily maintain a vehicle’s mobility even when punctured by using standard equipment with aftermarket wheels. This enables a driver to have more flexibility and time to choose the right location to get tires repaired.
In light of the awareness that tires do not really hold the weight of a vehicle – the air does – the size of the air chamber that’s formed between the wheel and the tire and the tire’s construction determine the real load potential.
Slow leaks are a direct cause of most flat tires, which renders it equally important to always monitor tires’ air pressure. However, tires that allow temporary use, even after air loss, are ideal.
Today, three technologies are used on vehicles to maintain mobility even when the tire is punctured. These are tires supported by an auxiliary system, self-sealing tires, and self-supporting tires.
Auxiliary Supported Run-Flat System
Example: Michelin’s PAX System of wheels and tires
This type of run-flat system put the onus on the wheel rather than the tire. A support ring is attached to the wheel in order that the flat tire’s tread will rest on it should the tire lose pressure. This system minimizes tire maintenance caused by tires that wear out or are in need of being replaced. Auxiliary supported run-flat systems promise a better quality of driving due to their sidewalls’ stiffness, which is equivalent to standard tires. However, the auxiliary supported system’s unique wheels do not accept standard tires. Also, their lower volume renders them far more expensive systems.
Example: Continental ContiSeal
Designed to fix the majority of tread-area punctures permanently, self-sealing tires feature a normal tire construction except for a puncture sealant lining inside the tire. Self-sealing tires provide a seal around the problem where it is punctured and then fills in the hole in the tread once the object has been removed from the tire. These tires immediately seal when punctured, so much so that the driver doesn’t know the self-sealing tire has just saved his bacon! Additionally, because these tires are standard in construction, loss-of-air symptoms warn the driver if the tire is really damaged beyond all possible repair.
Example: Bridgestone RFT (Run-Flat Tire)
Featuring a stiffer internal construction capable of holding the vehicle’s weight even when the tire has lost all its air pressure, self-supporting tires attach rubber inserts between heat-resistant layers of cord or next to them in their sidewalls. This prevents breaking reinforcing cords if tires lose air pressure. A driver may not even notice any sort of under inflation with this self-supporting system, which may cause increased tire damage if they fail to fix the tire promptly. Vehicle mobility is maintained for up to 50 miles at up to 50 mph with a self-supporting run-flat system.
Driving on Flat Run-Flat Tires
If you get stuck on the highway with a flat tire, you want to be able to keep driving long enough that you can get to the side of the road. This is the benefit of run-flat tires. They offer extended driving time, even after a puncture wound. That being said, they can prove futile if you drive on them for too long.
It is important that run-flat tires are only used on vehicles that have a dedicated Tire Pressure Monitoring System (TPMS) so drivers can constantly be aware when one of their tires has lost 25% or more of its recommended pressure. When the TPMS warning light illuminates on the dashboard, it means that at least one of a car’s tires is losing pressure. This warning affords the driver time to plan a way out of their current scenario, whether it is how to get to the shoulder or how to get to the nearest service station.
Run-flat tires depend on many factors to work properly, so their effectiveness can vary significantly depending on the vehicle, load, weather, speed, and distance traveled on them. When driving on run-flat tires, make sure to stay below 50 miles per hour and try to avoid driving more than 50 miles on them. Different run-flat tires can last anywhere from 25 to 200 miles, but 50 is a safe estimate. If you want more specific information for your vehicle, check your manual for what you can expect.
You should be aware of your driving and make safe changes to it when driving on run-flat tires because handling can change significantly. If you are aggressive on the accelerator or brake, it can be hard on the tires. Also be aware of potential changes if you are towing a heavy load or experiencing some other unusual condition.
After the TPMS light has come on in your vehicle, you should replace your run-flat tires. Manufacturers recommend this practice because there is no reliable, non-destructive way of knowing whether or not the tires sustained structural damage. Safety should be the first priority when driving on run-flat tires, so although you can drive 50 miles per hour, you should probably drive the slowest speed you can drive safely for the shortest possible distance to a service center.
How to Mount Run-Flat Tires
There are different types of tire changers used at service centers, so it is important to make sure that your service center has the right style to mount your run-flat tires. The two styles of “touchless” tire changers feature either rollers to undo the beads or side-shovel bead looseners. Rollers act to undo the beads as the tire is revolved around the changer, while the other style, side-shovel tire bead looseners, require a tire technician to flip, position, and rotate the wheel and tire assembly manually. To avoid potential errors by a technician, consider looking for a tire center in Kansas City that relies on the roller method.
Both styles of loosener should stay near the bead on the sidewall (next to, without touching, the wheel flange). If you place the looseners at a far distance from the bead, you can potentially open yourself up to damage to the tire’s rubber sidewall. An example would be a distorted sidewall caused by side-shovel looseners being placed incorrectly. This can be identified by cracks in the sidewall interior if you take the tire off the wheel.
To begin the process of mounting the tires with a bead loosener, you start with the backside tire bead and press only far enough to undo the bead from the wheel. You should apply lubricant to the wheel and the tire right as the bead is first pushed free from the rim flange. If you are using a side-shovel loosener, you must manually turn the tire assembly in order to be loosened. This turning process continues until the backside bead is loose. Then, you must repeat the process on the tire’s front until you undo the outside bead.
When removing the tire from the assembly, make sure to follow the tire machine’s instructions.
It is important to affix a new nickel-plated valve core, rubber grommet, and aluminum retaining nut to the original aluminum TPMS sensors before reinstalling the tire according to the tire machine instructions. You must make sure to torque all the pieces to the appropriate specifications in order to avoid air leaks. If you attempt to reuse any of the old pieces, you are susceptible to an air leak.
Run-Flat Tires – the Downsides
Though it may seem that run-flat tires are a no-brainer, there are in fact some downsides to running on them. For one, if you buy a car with run-flat tires from the manufacturer it won’t come with a spare tire or tools for replacing tires. Tire tread is generally reduced, meaning that run-flat tires will usually need replacing around 6,000 miles sooner than normal tires. They also cost about 30-40% more than similar traditional tires. They’re harder to find when you want to replace them, as not all Ford tire service centers in Kansas City carry them, and they can often make for a harsher ride as the sidewalls are stiffer than normal tires.