The Army Air Force requirements were for a trailer to deliver bombs to aircraft. It had to be low and maneuverable to get below the bomb bays of the aircraft. To arrive at the lowest possible height, a drop center rear axle was incorporated, and a castoring front axle with dual front wheels was used. Many have wondered why 750X18" rear tires mounted on 5 hole Budd wheels were used, as the more common 750X20 tires mounted on 6 hole Budd wheel would seem more logical. The answer was that having the lowest possible deck height was the reason. You now know why they used the odd ball 18" wheels.
It was found that the castoring front wheels were a problem on poor roads of primative airfields, an auxiliary spring was then added which allowed more load to be transferred to the pintle hook of the towing vehicle.
Some present day M-5 owners remark about the tow bar being difficult to hook up to their pintle, perhaps the reason for the auxiliary spring is now clear.
Tires for the M-5 appeared to be mostly commercial truck tread, I will have to check the M-5 SNL to see if a NDT is mentioned.
Ain't it refreshing to get off the topic of trucks for a moment?
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