As for the tyres, there is a picture of a Jeep in Berlin with four diffrent sizes of tyres and a piece of metal bolted across the side wall of one.
Intresting fact Dodges were shipped to the UK on skinny tyres with no spare. Remember at that time most rubber came from Malaya, and who had Malaya at the time?
The top one is from the defences of the Panama Canal. Though why Mortars I don't know.