Applied to the rotation property, creates a layer that rolls realistically (without slipping) when you drag it horizontally.
Code Sample
Hover over the code and click the copy button.
var circumference=content("My Shape").content("My Shape Path 1").size[0]*Math.PI;// Or replace everything before "Math" with the pixel width of your shape or layer object.
var distance= transform.position[0] - transform.position.valueAtTime(0)[0] //if your wheel layer is parented to another layer, use the x transform position values of the parent layer
(distance/circumference)*360
Other Notes
Note that in this walkthrough, JJ Gifford makes assumptions about width, scaling and starting position values that may not be applicable to all use cases. The expression code above is adapted to be more generally usable.