Our wheel nuts are torqued to manufacturer specifications, and are then fitted with high-visibility wheel nut indicators. The indicators are fitted in a uniform pattern, so when a wheel nut has loosened, the indicator will become out of sequence. The wheel nut indicators are also heat sensitive. If there is a binding brake or seized bearing, the heat is transferred through the stud and nut. If this temperature exceeds 120º C (248º F), the indicator will start to blister around the circumference and eventually start to distort. Pre-flight walkaround checks now can include wheel nut checks.