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Discussion Starter · #1 ·
hi there,


i was hoping to know how runflat tyres comunicate the tyre pressure data with computer in the car. having a look the back of the wheel, there is no wire or what so ever.

can some body please tell me some information please. thanks.
 

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Discussion Starter · #5 ·
right.. icic, so, what i know now is, the car computer actually detecting the wheel speed instead of the real pressure of the tyres.

am i right?
 

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That is correct. There is nothing in the wheel to determine the pressure. Basically what happens is that if one of the tires is running slower than the rest then the system determines that you have a flat and the light comes on.
 

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Making it add up
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That is correct. There is nothing in the wheel to determine the pressure. Basically what happens is that if one of the tires is running slower than the rest then the system determines that you have a flat and the light comes on.
Surely you mean faster not slower!
 

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Surely you mean faster not slower!

To be honest, I am not 100 percent certain. However, I would go with slower as the drag of the flat will cause the tire to "fall behind" thus it is slower not faster. Perhaps someone with a better understanding of the system can elaborate.
 

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Rocking the F57
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Slower ;)

Due to the runflat technology and the stiff supporting sidewall, the diameter of the wheel does not drastically change when pressure is lost.

The increased friction however of the uninflated tyre on the road causes it to turn slower than a normally inflated wheel - thus triggering the sensor.
 

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Slower ;)

Due to the runflat technology and the stiff supporting sidewall, the diameter of the wheel does not drastically change when pressure is lost.

The increased friction however of the uninflated tyre on the road causes it to turn slower than a normally inflated wheel - thus triggering the sensor.
I was not convinced and found this article which supports my initial thought.

Dunlop Tyres UK
 

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i'm not sure i'm going with the friction makes it slower to set the sensor off. because i don't think they will put different sensors in cars with run flats than cars without runflats. even if you do have run flats the tyre does go down slightly - making the wheel rotate faster and thus setting the trigger off.
 

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If the sensor just measures a speed difference the sensors need not differ. But, like you, I did not believe the increased friction hypothesis and Dunlop says I am right.
 

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indeed you are - and thats what i would have thought. because with non runflats it wouldnt be a different sensor/system
 

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I didn't mean that it is an increase in friction that sets off the light. It is speed difference that does it as mentioned. The question is to wether the tire is faster or slower as it flattens. Either way the question is answered.
 

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Runflat technology depends on a reduced rolling radius as the sidewall "collapses" slightly to bring the rubber together and support the car.
That's why I depend on it to warn me when my non-runflat tires are low.
The rolling radius decreases and the speed at the axle increases.
 

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Discussion Starter · #17 ·
from what i read so far. i don't see any reason that if i change to none-runflat, and i have to switch off the tyres pressure monitor off. am i right?
 

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You are exactly right.
I've switched to non-runflats and I've used it to alert me of leaks so I can repair the tire before it goes completely flat.
BTW, all cars sold in the US are now required to have a tire pressure monitoring system similar to the MINI one, even though only a small number come with runflat tires.
 
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