A lining wear measurement system which accepts signals from a plurality of movement/displacement sensors coupled to respective auto-adjusters of vehicle brakes and giving information about prevailing brake pad/lining thickness. The system includes a means to hold internally a target wear-out point representing a minimum acceptable brake lining thickness based upon the characteristis of known linings and an internally stored starting point which is set in automatically at a suitable point in time after the brake has been equipped with a set of replacement linings so as thereby to take account of the reducing disc or drum thickness as the life of the brake progresses. Alternatively, the system can hold an internally stored starting point which is arranged to be manually initiated but actually stored at some suitable point in time thereafter upon each set of replacement linings being installed. The system can also recognise an opening up operation of the brake, such as is necessary to remove worn linings for inspection or replacement purposes, by comparison of pre-opening and post-opening brake position readings.