Here is one for you.
The hydraulic motors I have selected for my machine have a maximum sideload of 2000lbs.
Now these are on the front of the machine, and there is another set of wheels on the rear., assuming the power unit (engine) which weighs 100 lbs and is centered between the centerline of both axles, one can assum the load is divided between the axles or 50 lbs and 50 lbs rear. When an additional load of 200 lbs is added 3 feet ahead of the front axle, What does that do the weight on the drive (front) axle? Is it as simple as a torque calculation, or more intense?
Given that the front axle already has 50 lbs on it and the extra load is 3 feet ahead on that 200lbs X 3 feet is 600 ftlbs, does that translate to 650 lbs on the front axle? Or is the actual load higher than that?

If the 100# Engine is 6' behind the Front Axle it will offset your 200# load 3' in front of that axle and the Front axles will have a combined load of 300#.

If the 100# engine is only 1' behind the front axles then the front axles will have a load o 300# until the back axle raises off the ground and the 200# load contacts the pavement.

At that point the load will be partially held up by the front axles and the ground.