half a mill to 1mm not difficult to set don't need to realy it its undamged evn if it did its esy enough to do (assuming you get move the dan things there such a pain to get out you end up ruining them anwya.If you do, get them to fit a genuine renault part!! The abs sensor which sits abouve the ring sometimes needs to be set up to get a clear reading if it's been boshed by the split / loose ring, it's a daft measurment aswell (set to fractions of a mm) so i'd be suprised if you can do it by eye.