Actually it's very EASY to overload an axle while still UNDER payload.
Put a 3000 lb pallet of sod, concrete blocks/paver on and in the very back of an 8' box truck with a 6000 lb ra capacity. You will probably be over the approx 3500 lbs of load capacity for the axle rating.
You will lower the rear enough that you start pulling wieght off the FA onto the RA, putting it over it's capacity.
Yes been there, done that.ore fingers and toes counting than grit and I have combined.
Likewise depending upon the truck bed length, you can put a load in the very front of the bed, for my IHC, 4-5000 lbs in the front 4' of the bed on pallets will add 2000 lbs to the FA overloading the 8000 gfaw of that truck. It has typically about 5900 on it empty. 12000 lbs to axle limits, 14000 to legal registered legal weight limit.
Reality, very easy to overload an axle! That is the way MOST commercial drivers get over wieght tickets, by not balancing the load so an axle is not over wieght, but under there paid for gvw.
Marty