Opel COMBO Owner's Manual page 141

Driving and operating 139
The maximum permissible vertical
coupling load (60 kg) is specified on
the towing equipment identification
plate and in the vehicle documents.
Always aim for the maximum load,
especially in the case of heavy
trailers. The vertical coupling load
should never fall below 25 kg.
Rear axle load
The permissible axle loads (see
identification plate or vehicle
documents) must not be exceeded.