According to the guide 23mm is the covert, but since my previous owner turned off the ufo`s at the beginning of the day, and I already have the 2nd set of blocks on it, I have after a measurement yesterday to horror only 21,5mm per disk, but no big edges, but my blocks are still good! now my question, can I still drive the blocks, or do the slices need to be changed in an emergency, since it is too dangerous with this thickness of the disk? I have absolutely no unbalance or bad brakes!