Tell me how you would check the tyres to ensure that they have sufficient tread depth and that their general condition is safe to use on the road

Tyres should be checked to ensure there are no cuts or bulges. There should be 1.6mm of tread depth across the central ¾ of the breadth of the tyre and around the entire outer circumference. This can be checked with a tyre depth gauge or the depth markers in the tyres themselves.