The change in the vertical distance of the frictional material on the pad is referred to as brake pad thickness. It is indeed an incredibly useful value to measure the distance of pad wear and to identify when a replacement is required. New brake pads usually have a value between 10mm to 12mm. With every break taken, the pad wears down, which results in reduced thickness. Recommended friction material to replace in the pads ranges between 2 to 3mm if the goal is to ensure effective braking performance