"The Natural Philosopher" wrote in message
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On 23/06/18 14:28, John Rumm wrote:
On 23/06/2018 06:56, The Natural Philosopher wrote:

https://www.youtube.com/watch?v=_2l5bOhHNxU

Answer. not by very much, if at all.

So the short answer to your question is "yes".

This seems to be a perpetual urban myth.

Which you have just agreed with by claiming there is a small change.

No the urban myth says that since there is say a 10% change in what
peooplle think is 'the radius', therefore the RPM will be 10% slower.

No one said that the change will be the same percentage,
just that when the distance between the axle and the ground
changes, that the rotation rate will change and that change
can be measured.

It tyre pressure sensors are using this, it has to be a very very
complicated bit of software to detect - say - less than 1% change in RPM
relative to the other wheels.

Can't see that being too difficult in itself - especially as you probably
have input from other sensors and know the steering angle input and so
can assess when you are driving straight and not under high acceleration
etc.


Why would there be monitors on steering angle?


Type pressure monitoring will need to be more sensitive to rate of change
than absolute difference since unequal tyre wear would otherwise be
flagged.


Well teh way it aseems to work is that one wheel will overotate with
respect to its diagonal consisetntly.

But not by very much.

But enough to measure with RPM so easy to measure differentially.