This informaition is important as it determines whether the disk can be machined or not.This measurement,always engraved on a visible area of the disk surface,is also written in the repair manual.It does not usually correspond to the limit allowed for disk resurfacing,but rather to the minimum thickness of a worn disk.In other words,aresurfaced disk of this thickness cannot be used.A disk that is too thin may become deformed due to wear and even break when the brake is applied.Disk thickness is measured with a micrometer.