View Single Post
  #4   Report Post  
Posted to uk.d-i-y
Andy Burns[_13_] Andy Burns[_13_] is offline
external usenet poster
 
Posts: 7,829
Default Does a tyre change its CIRCUMFERENCE when underinflated?

The Natural Philosopher wrote:

https://www.youtube.com/watch?v=_2l5bOhHNxU
Answer. not by very much, if at all


looked to be half the width of a piece of insulating tape per
revolution, what was even the point of only measuring the rolling
distance once?

This seems to be a perpetual urban myth.
It tyre pressure sensors are using this


And iTPMS systems *are* using it

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.


Little extra complication within the ABS unit, how many pulses per
revolution does it process from an ABS reluctor ring? 40 to 60 "teeth"
seems common. If the ABS unit can detect wheel slowing (i.e. a skid
starting) then it can detect a wheel speeding up (e.g. from a puncture)

Nobody is suggesting it decides if it's a puncture within a single
revolution, it detects over a period of time, 1% isn't that tiny.

I noticed the actual TPMS trigger often tended to be when you put your
foot down going round a corner/roundabout.