Fitted to a number of BMW vehicles and available from tyre retailers, run flat tyres aim to reduce the need for stopping immediately if you score a flat tyre. CarAdvice reader Sandra wanted to know why her tyre replacement cost was so high and whether she should keep run flat tyres on her BMW X1.
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Q: Hello. I own a BMW X1 and it is due for a tyre replacement. The price for these tyres is quite expensive and when I asked why, the dealer told me it was due to them being 'run flat' tyres. What does this mean? And why are run flat tyres so much more expensive?

A: Run flat tyres feature on a number of BMW vehicles and were originally designed to help minimise the need to pull over immediately when you puncture a tyre and it begins deflating.

These tyres feature stronger sidewalls — often steel reinforced — that remain intact when the tyre is punctured. The purpose and idea is that you will still be able to drive on the tyre until you are able to get to a service centre to have the tyre fixed or replaced.

Given the nature of the tyre construction, these tyres are often more expensive — generally around 25 per cent more — but come with the added value of convenience. They also reduce the vehicle's running weight (as you don't need to have a spare tyre and jack in the vehicle), but can affect the ride quality (due to the construction of the tyre).

Run flat tyres normally have a recommended speed limit of 80km/h and can be driven with for up to 150km when punctured. If you aren't keen on getting your hands dirty when you get a flat tyre, run flat tyres offer a middle ground between convenience and practicality, but come at a cost when it comes to replacement.

Check out our video to see an example of how a car behaves on run flat tyres. You can also read more about run flat tyres in our recent technology article.