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Run Flats Hmn

louis crawley

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Hi there im new to this forum but find it very useful and interesting im louis im from notts and own a 2001 sc 430 with 41,000 miles im overwhelmed with the cars performance but some how i dont like the feel of the runflats has any one any experience with this tyre should i change

appreciate your comments


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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.....

Attached Image

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 accomendate 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.

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Cant ask for anymore info than that. :D

Also i notice your from Nott's, hopefully you'll be able to make it to some of the meets we're having soon. Theres one in Stafford on 10th June if you can make it along to that one mate.

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:winky: Hi all and thank you for your help and all your answers to my questions

i now have more of an idea re run flats i will decide over a weks sleep ....

i would love to come to the meeting in stafford hopefully i will be able to make it i will keep in touch thanx again

louis :winky:

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