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Run Flat Tyres


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Are these only for cars that have tyre pressure sensors or somthing? or can they be fitted on any car?

I was thinking of getting a set for my Gs300 Sport MK1 but was not sure if these would be ideal or should I stick to standard sets?


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The 'RFT' concept does have a point regarding safety and hazard, but the evolution belays a few convenient areas not on public in true wim fashion........


The RFT can resist and react to most forms of deflation, sudden or progressive and permit the driver to continue with the journey regardless of the deflation, valuable for safety and it assures the owner that nothing would deny the destination other than fuel or the M25.


The concept has been realised over many years, Dunlop suggested the 'Denovo' which was a tyre locked between a split rim, this wheel had no internal recess that allowed the tyre to 'off-set' and detach from the rim, this also involved internal canisters that would be crushed and released a gel to keep the tyre cool... at the time the concept was very expensive and ultimately failed, apart from cost the fundamental flaw was if the tyre deflates then it was 'scrap'

Following this commercial failure Dunlop abandoned the concept of the 'split rim' and introduced the 'Demlock' tyre, this carried the same concept and placed the gel in the tyre without the canisters..... a new evolution of wheel was designed to support this but very costly... in fact Jaguar was the main recipient and offered this safety factor deep within the sales campaign... again this failed.. fundamentally for the same reason if the tyre deflates it is 'scrap'.

Then things went quiet..........

Very quiet!

With the birth of the new Mini One/Cooper in 01 Pirelli answered the run flat question again with the 'PAX' design of tyre and rim, basically the rim has internal shoes that supports the tyre and simply replaces the air after deflation... but a new problem was born?.... not only was the tyre scrap after deflation but now only the main dealer had sufficient machinery to remove/ replace the tyre, in time ultimately i feel this will also fail.

Today's evolutions expand on past examples, now the RFT will fit any rim and most shops should be able to fit/ remove the tyre.... but something is missing?..... where is the gel.... where are the internal shoes.... what keeps the tyre cool once deflated?


The evolution is evident, make the tyre wall armoured and it will suspend the car.....

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So they did...... the new Goodyear and Bridgestone are now OE within BMW and associated marques, Pirelli have taken a back seat for now..... but there is still a problem?

The tyres needs to communicate with the car directly via internal censors or externally via the ABS, visible activation on the dash will need to be re-set/ turned off by the dealer, this i feel angry about! (another topic maybe)

A warning

If you have RFT then it's a done deal... due to the armoured construction of the tyre the suspension has been 'down graded' to accommodate the tyre, you cannot deviate from the set-up unless the suspension is also modified, so in essence the tyre/ suspension is a package and must be considered as final.

Oh and to add insult even the new variations of 'run flat tyre' once deflated is 'SCRAP'

Topic taken from the wim forum

Hope this helps

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