Gan, 1960's, Search and Reascue Shackleton . On walkaround the F.E. discovered a cut in one of the tyres. No problem, Gan was required to keep a spare Shack. wheel/tyre assembly at all times.
Suppliers refused to release it, because if they did they would not have one available, and that would be against the rules.
Very short discussion between the Shack. Captain, the Supply Officer and the Station Commander.