I am considering purchasing either a Toyota Prado GXL or a Mitsubishi Pajero. The Prado has a 2500 kg towing capacity while Pajero has 3000 kg. The caravan I am considering has a tare of 2100 kg and weighs 2500 kg when loaded. The caravan dealer has told me the caravan has a 160 kg tow ball weight. Can one calculate actual tow ball weight from towing capacity?
No. The manufacturer determines the vehicle's towing capacity taking into consideration things like the design of the vehicle, its rear axle load, tyres and the effect the trailer will have on the vehicle's attitude and stability. You can measure the tow ball weight using bathroom scales, or putting the laden trailer across a weighbridge and getting the weight borne by the axle/axles. The tow ball weight will be the total weight minus the load on the axle/ axles. It's generally about 10 percent of the total weight of the loaded trailer.