Run Flat Tyres – Everything You Should Know
What are run flat tyres and how they work?
For years together we have relied on conventional pneumatic tyres to give us a nice comfortable ride. But, once in a while, they blow out or they lose their air if pierced by a sharp object. So, we have always carried a spare tyre. But these days the spare tyres are disappearing, thanks to the entry of run flat tyres. As the name implies a run flat tyre is a tyre that can run even when punctured. The world’s first run flat tyre was introduced by Michelin in the mid-1930s for military purposes. This breakthrough innovation in the tyre industry was expensive to be integrated into the regular passenger cars at the time. Later, other tyre manufacturers stepped in and further worked on the technology in the 1950s and 1970s.
What are run flat tyres?
As opposed to the conventional tyres, run flat tyres keep you going in the event of a puncture, helping avoid potentially dangerous situations on the road. In case of a puncture, run flat tyres allow you to continue your journey at speeds of 80km/h. It’s all down to their reinforced self-supporting sidewalls which keep your vehicle stable and drivable for up to 80 km. In this way, the run flat tyres save you the hassle during an air pressure loss situation and let you drive for 80 km at a reduced speed of 80 km/h, sufficient to get to the nearest tyre service center safely. Due to these safety reasons, the run flat tyres are now-a-days fitted as Original Equipment (OE) to most of the luxury cars.
How to identify run flat tyres?
The tyres designed as run flat can be identified by the sidewall markings. Since the run flat technology has been developed and improved by many major tyre manufacturers, each one has its unique code of indicating a run flat tyre. Some of them are listed below:
- Michelin: ZP Zero Pressure
- Bridgestone: RFT Run Flat Tyre
- Continental: SSR Self Supporting Run Flat
- Dunlop: DSST Dunlop Self Supporting Tyre
- Goodyear: EMT Extended Mobility Tyre
How do run flat tyres work?
Run flat tyres can run for 50 mph after getting punctured. How they do that is interesting. There are primarily two run flat tyres types: 1. Self-supporting 2. Support ring.
1. Self-supporting
This is the most common type of run flat tyre. Similar to a conventional tyre, a run flat tyre also uses pressurized air to support the weight of the vehicle. In a conventional tyre when a puncture occurs the air immediately leaks out and the tyre completely deflates. A run flat tyre, on the other hand, has a fallback plan to keep it running in case of sudden puncture – its robust reinforced sidewalls. Stiff and durable sidewalls support the vehicle’s weight, preventing the tyre cord from touching the rim.
2. Support ring
In the support ring system, a ring usually made of hardened rubber is used. This special ring ensures rigid support along the entire circumference of the tyre. The tyres with the support ring technology can withstand heavy loads. And should a puncture occur, the tyres can be driven up to 80km.
While the regular tyres depend on air to support the vehicle, the run flat tyres depend on their strong sidewall structure or the support ring to carry the weight of the car with less or no air pressure. However, these tyres are designed to temporarily support the vehicle in case of a puncture and hence, you cannot drive beyond a specific distance after the tyre is deflated. The drop in the air pressure is indicated by the Tyre Pressure Monitoring System on the dashboard panel of your car. The speed limit and distance that a flat tyre can cover could vary depending on the tyre manufacturer.
Can you fit run flat tyres to any car?
Run flat tyres necessitate the installation of a Tyre Pressure Monitoring System (TPMS in the vehicle to alert the driver of a low tyre pressure issue. The low air pressure in the normal tyres is easily noticeable due to the sidewall deformation. The strengthened sidewalls in a runflat tyre remain stiff even in low or zero pressure condition making it almost impossible for the driver to notice the puncture. Hence, run flat tyres should only be fitted to cars that have the Tyre Pressure Monitoring System (TPMS) installed so that the driver receives an alert signal in case of a puncture. This signals the driver to reduce his speed and keeps him aware of the limited distance he can travel with those tyres on.
Most of the luxury passenger cars these days are originally fitted with run flat tyres. However, if you wish to fit the run flat tyres to an older car, the TPMS can be retrofit. Another point to be noted in this case is that the suspension of your car might also require some modifications to be fitted with run flat tyres. In any instance, the general rule of thumb is to always check your car manufacturer’s recommendations while replacing tyres.
Can run flat tyres be repaired?
Whether a run flat tyre can be repaired or not depends upon the tyre manufacturer. In most circumstances, a new tyre will be required. Unless it's merely a puncture in the tread and you detected it early, the run flat tyres cannot be repaired. For example. Michelin ZP tyres can be repaired only once under certain guidelines following a thorough investigation done by a tyre professional.
Advantages of run flat tyres
In terms of ride comfort, they are almost indistinguishable from standard tyres. Along with this, run flat tyres come with several other benefits as mentioned below:
- You don’t lose control of the vehicle in case of a blowout
- You don’t have to replace the tyre immediately
- You don’t have to keep a spare wheel in your car
- You save weight since there is no need for a spare tyre or wheel changing equipment thus, making your vehicle more fuel efficient
- Run flat tyres withstand mechanical damages better
- You can save on roadside assistance services
The run flat tyres are expensive as compared to conventional tyres. But, the additional expense can actually be a shrewder purchase for the extra time they give you to safely get to a place where you can have them replaced. They are available at the TYREPLUS centers near you.