The Gross Allowable Weights, GVW, for 1939 Chevrolet Trucks are shown here.

Let's say you have a light Light Delivery Truck (1/2 ton truck) that had 6.00x16" wheels 4 ply tires from the factory.
The GVW (Gross Weight) would have been 4,400 lbs.

So, I think the digit that goes to left of the 00 in the upper entry box should be a 40, giving a 4400 Maximum Vehicle Weight?