DIYbanter - View Single Post - Does a tyre change its CIRCUMFERENCE when underinflated?

Andy Burns[_13_]

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.