"Andy Burns" wrote in message
...
The TPMS operates over a longer period of time, probably minutes rather
than seconds, so over many revolutions of the wheel, likely the numbers
will get averaged out before it decides one wheel is turning faster than
the others enough to flag it up.

It *has* to integrate over a fairly long time and number of rotations to
avoid it being triggered every time the car turns a corner and the outer
wheel rotates faster than the inner wheel. I would imagine (and I've not
done the calculations) that the difference in rotational speed between inner
and outer wheel on a bend will be significantly more than the difference in
rotational speed between a correctly-inflated and an under-inflated wheel,
so any TPMS has to average out this large difference in order to be able to
detect a much smaller one.