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Run-Flat Tyre Guide

August 22, 2018
Run-Flat Tyre Guide

Unfortunately, at one time or another, most motorists will suffer the inconvenience of a tyre puncture.

There are inherent dangers associated with changing a wheel at the roadside. In particular, if the puncture occurs on a freeway where the work has to be carried out on the road shoulder, where possible motorists need to avoid the risk of being stranded.

While a puncture is usually more of an inconvenience and unwanted expense, the dangers involved with a tyre failure at high speed are far more serious, with the greatest danger being a complete loss of control of the vehicle. This occurs when the sidewall of the tyre, which is usually kept secure against the wheel by the internal air pressure, becomes separated and drops into the well of the wheel.

What are Run-Flat Tyres?

Run-flat tyres are designed to keep the all parts of the tyre secure and where they need to be, even when operating at zero pressure.

Compared to a normal tyre, run-flat tyres have a reinforced sidewall which stops the rim of the wheel touching the road, if the tyre loses all of its inflation.

While being subject to distance limitations, run-flat tyres allow the motorist to continue their journey without having to stop and replace the punctured tyre.

Once the Tyre Pressure Monitor Sensor registers a loss of pressure in tyre this will be displayed to the driver on the dashboard of the vehicle. The Tyre Sidewall will slowly collapses as it is continued to be driven on at a reduced speed, until such time as the driver can safely stop to have the tyre seen to. The tyre will be inspected to see if the tyre can be repaired or will require to be replaced depending on damage to the tyre and tyre manufacturers guidelines regarding repairs.


Types of run-flat tyres

Typically, run-flat tyre systems can be split into two categories:

  • Run-flat tyres with a strengthened sidewall

  • Run-flat tyres with an internal support ring that is mounted on the inside of the wheel rim

Although tyre manufacturers have adopted several different run-flat systems over the years, all run-flat tyres have one goal in mind - vehicle and passenger safety.

Due to increasing popularity and focus on driver safety, more and more car manufacturers are offering this as a factory fitment option on various models.

Run-Flat Tyre Limitations

Speed and distance limits: Although run-flat tyres allow you to continue driving with a puncture, you should ensure that your speed is limited to a maximum speed of 80km/h. The manufacturers have advised that the tyre may last up to 80km of travel in this circumstance. The idea behind this is to give the driver enough distance to safely reach a suitable location to safely get their vehicle and themselves out of harms way.

Higher rolling resistance: Having a reinforced tyre wall makes the tyre heavier, which increases the rolling resistance. This makes the motor work harder to drive the car which decreases fuel economy. However, this is somewhat offset by not having to carry a spare wheel when you have run-flat tyres equipped.

Limited tyre options: As the popularity for a Run Flat tyre has increased, the range of sizes and brand available has increased. This means that there are more options for the owner of a vehicle fitted with Run Flat technology

Limited vehicle options: Typically, run-flat tyre systems are pre-built into your vehicle, meaning that if your car came with run-flats off the factory floor, you should use them as these tyres have been designed to most effectively work with you vehicle suspension and braking systems. On the other hand, if your wheels aren’t designed to accommodate run-flat tyres, you won’t be able to use them.

There is a range of run-flat tyres which are deemed not repairable by the tyre manufacturer. If you are unsure, please check with your local Bob Jane T-Marts as to the specific manufacturer recommendations regarding repairs to and pricing for your run-flat tyres.

Tyre Pressure Monitoring System

The other essential item of safety equipment for any vehicle is a Tyre Pressure Monitoring System (TPMS). This system, which is now being found on most modern vehicles, lets the driver know when a sudden loss of pressure has occurred on one or more of their tyres.

When an alert is shown, that signals the driver that the tyres need to be checked or changed as soon as possible, either through a specialised tyre retailer or their vehicle manufacturer’s service centre.

Run-flat tyres are designed to minimise the difference in ride quality when a tyre is punctured. This is especially the case with freeway driving where there is relatively little cornering.

For this reason, it is difficult to determine whether a tyre has lost pressure or is operating in zero pressure conditions. Should the driver not be aware of a loss of pressure they may well exceed the safety limits imposed by the manufacturer.

There is a range of run-flat tyres which are deemed not repairable by the tyre manufacturer. If you are unsure, please check with your local Bob Jane T-Marts as to the specific manufacturer recommendations and pricing for your run-flat tyres.

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