On 25/06/2018 12:00, Tim Streater wrote:
In article , Huge
wrote:

On 2018-06-25, Andy Burns wrote:
Huge wrote:

Andy Burns wrote:

there isn't a single distance from the centre of the axle to all
parts of the tyre in contact with the road ... the average distance
perhaps?

This is really, really simple. Why are you all making it so
complicated? (It's the *shortest* distance, obviously. Just draw a
bloody
diagram.)

The diagram I linked to yesterday seems suitable

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


Because it's wrong. In this context, the relevant dimension is O - Q.
How
could it be otherwise?

One revolution of the wheel has to equal one passage of the tire's
circumference along the road (since the tire does not slip around the
rim and assuming no slip on the road). How could it be otherwise?

Talk of "effective radius" is not relevant.


If by "effective radius" you mean the rolling radius it is the only
relevant measure to combine with the angular velocity in order to arrive
at the speed of the vehicle[1]. If you dispute that please post your
equation.

Or of course you could admit that by circumference you mean the rolling
circumference - defined as 2 x Pi x the rolling radius - which changes
with pressure.



--
Robin
reply-to address is (intended to be) valid