Run flat tires or zero pressure tires as it is alternatively referred to, appeared in the market in the mid 1980s. Being relatively new, it was slow to catch on as most users were unsure of the benefits of this new concept tires. After establishing that these tires are clearly safer in an emergency blow out situation, vehicle manufacturers took the lead to adopt these tires as standard fittings.. Today, about 10 to 12% of luxury/ performance vehicle manufacturers have adopted run flat tires(RFT) as original fittings to their range of vehicles.
Before we go into details of run flat tires pros and cons, let us try and understand how a run flat tire is constructed and how different it is from regular tires.
In any pneumatic tire, compressed air in the tire and the side wall of the tire play a major role in supporting the weight of the vehicle during its operation. In the event of loss of the air due to a puncture, there is no more support from the column of air and the entire weight is borne by the side wall of the tire. With a standard tire, the driver is unable to continue to drive the vehicle as loss of directional control becomes evident. If the driver still continues driving the vehicle, there is every possibility that the tire may dislodge from the rim resulting in rim and tire damage.
In the case of a run flat tire, the side wall is specially reinforced with hard rubber compound that will continue to support the weight of the vehicle in the event of a blowout. Depending on tire manufacturer and vehicle manufacturer preference, there are basically two different systems employed in run flat tires.
- Self supporting system- a specially reinforced side wall construction that will not allow total collapse of the tire in the event of zero tire pressure. The vehicle weight can be supported and the vehicle can still be maneuvered safely to the nearest point for assistance.
- Support ring system-this method employs a highly durable material band that fits around the inside of
the specially designed EH2(Extended Hump)tire rim which will support the weight of the vehicle in the event of a zero pressure condition. This also allows for safe maneuvering of the vehicle to the nearest point for assistance.
Now that we understand how the run flat condition is satisfied by using either the self supporting system or the support ring system, let us look at the pros and cons of using these tires as standard installation on our present day vehicles.
- In the event of a blow out during high speed running condition, the tire will not go totally flat and the vehicle can still be controlled as per normal without causing any undue panic to the driver and other road users. In terms of safety and reliability, this is truly a plus point.
- The vehicle can still be driven at a speed not exceeding 80kmh for a distance of at least 80km to seek for assistance.
- A vehicle with standard run flat tires do not require a spare wheel, a jack and tool kit. Space and weight is therefore saved.
- In the event of irreparable or end of life replacement, the cost of replacement is much higher compared to non-run flat tires.
- Must be used with Tire Pressure Monitoring System(TPMS). This is mandatory as loss of pressure is not easily noticeable without a pressure monitoring system during driving.
- Poor ride comfort or harsher ride condition due to stiff tire side wall.
- Not popular and not readily available with tire dealers. Have to order and wait.
- Reduced tread life also due to stiff side wall used to support vehicle weight in case of a puncture.
- Tire manufacturers do not recommend repairing a run flat tire that has punctured. Replacement is recommended for safety reasons due to uncertainty of internal condition of the tire.
- Specially designed rims are required for run flat tires and after market supply for such rims is very limited.
Judging from the facts that we have gathered so far, it is quite clear to us as to why run flat tires have not really caught on well especially in the replacement market.
Feedback from consumer forums and reports clearly show low customer satisfaction levels in the field of cost of replacement, ride comfort and lifespan of the tire.
Tire manufacturers are clearly aware of such low customer satisfaction levels and we hope to see an improvement in these areas in the coming years.
It is clear that customers who have good ratings for run flat tires are customers who have experienced the safety and reliability of these tires particularly in a sudden blow out situation during driving.
If you are in the market for a set of new tires, for regular or run flat tires, you can now make an informed decision with what you have acquired from `Run flat tires pros and cons.
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