How much play/movement is allowable

 

Very little. The process when fitting bearings is to take up all the slack with the securing nut until there is no play, then back off one flat maybe two, then secure the nut with a split pin. The bearings must not be done up tight. I can't remember how much play you get at the tyre tread, but it must be detectable, although not excessive. It is a bit subjective, I'm afraid.