On 24/06/18 21:04, Andy Burns wrote:
wrote:

Everyone seems very fixed in their ideas about this

I think it all comes down to the distortion of the tyre and the reduced
length of the flat chord BA vs the arc BPA that would exist if it wasn't
loaded at all.

http://the-contact-patch.com/book/road/c2020-the-contact-patch#figure-ERr

the more heavily loaded, or the less pressure it's inflated with, the
greater z will be, and the smaller the effective rolling radius, reading
through to the end of that page gives chapter and verse formulae ...

In short the flatter the tyre, the smaller the effective radius and the
faster the wheel needs to rotate to keep up, which is what the sensors
detect.

No. The effective radious first of all is almost ********. But if you
mean te circumferenmce divided by 2 PI then that will only change with
pressure, as the belts strech, Not with loading.

Otherwise p[eole would be travvling 30% slower when their tyres were
flat, for the same speedo reading



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