Vehicles that have been abandoned and have no tires on them should despawn instead of remaining where they are. This is especially true for the truck which requires so many tires that it's completely impractical to get running when someone leaves it behind and strips off the tires.
Alternatively, make tires not despawn so people can't just remove the tires and grief the server with abandoned vehicles.
i dont know if this would be a good game mechanic. the engine has to be ruined to have a vehicle despawn - i think thats fair enough.
but i would like to see tires and other parts (doors, engine parts) of a vehicle been locked by default when they spawn. that would help against the griefers and gives another task for the survivor, if he just wants to "steal" the radiator to use it for another vehicle. we already got the tools and possibility to lock parts, so it would be a nice small addition.