Core: Nose weight of the centre-axle trailer

The rule applies specifically to the centre-axle trailer (Book p.230): wheels roughly in the middle, drawbar resting on the tow ball — most caravans and boat trailers. Under 750 kg permitted maximum mass, 50 kg is a hard ceiling: too much downward load overloads the tow ball and pushes the car's rear down. Above 750 kg it flips: too little nose weight makes the trailer unstable instead. That minimum is 1% of the permitted maximum mass — at 1,200 kg that is at least 12 kg. The well-known '75 kg' comes from quick-prep rules of thumb for unknown manufacturer specs, not from this book — don't confuse it with the max. 50 kg or the min. 1% rule. A nuance the book itself does not state: that 1% minimum does not keep rising without limit. Per the vehicle regulations the nose weight never needs to exceed 50 kg, even though 1% of a still heavier TMM would arithmetically be higher — at 5,000 kg TMM the minimum already plateaus at 50 kg.