wouldnt the tire slip with some or all of the rubber nurling gone on the dyno drum
When the knurling gets really worn you end up pulling the straps down a bit tighter.
There is always some slip, its just about keeping it to a minimum.
For those of you who are not too familiar with slip on the dyno, this may help you to understand.
Here is a good example.
This is a k6 1000. Look at the dates and times at the top. It is 6 successive roll-ons on a cold tire.
The left hand graph is you normal power graph and the right hand one is the tire slip graph.
But if you change to a low reading tyre the slip graph does not change. It really is not a measurable thing how much the rubber sticks to the roller.