A tractor-semitrailer has a maximum authorised mass of 40 000 kg. Unladen combination mass is 14 500 kg. What payload figure should the driver start from under Goal 1.4?

1. 40 000 kg, because that is the plate mass
2. 14 500 kg, the unladen mass
3. 60 000 kg, adding tractor and trailer plates together without combination limits
4. 25 500 kg, which is maximum authorised mass minus unladen mass, then reduced further for axle limits, volume and remaining fuel and equipment