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      12-22-2012, 06:02 PM   #13
Major General

Drives: BMW F11 535i Touring
Join Date: Mar 2007
Location: Scotland, Highland Region

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Plus some markets don't have RFTs the same way as the UK specifications, F30 included.

What is in dispute... has been from when RFTs were first introduced, exactly what does BMW do to 'tune' for RFTs? Certainly was asked in the beginning and to a degree can still be asked today.

Where we have options for RFT upgrades, for which tyres was the chassis set up? As suspension parts don't change with tyre options. So if you buy say an X3, which has RFTs fitted due to the wheel upgrade, removing them and fitting non RFTs is no more than returning the vehicle to base specification. Which is the 'safe' chassis?

All the comments through the years on being dangerous, waiting for an accident to happen and scare stories was completely unfounded on BMW specification alone. Let alone when BMW/Bridgestone demo tested the 3G RFTs against 2nd generation and standard tyres on the same E60 chassis, to try and prove 3Gs were as good as non RFTs. So what was that all about if the chassis was designed and setup for RFTs?

A lot of questions have been asked of BMW on this "tuned for RFTs" over the years and the official answer is never convincing. The unofficial view has been a bit different. Some track tests on the Z4 have shown running non run-flats, on the "designed for run-flats" chassis is the better handling car.