1. on a truck, which does not tow a trailer if:
* the truck's actual weight, registered gross weight or gross vehicle weight rating exceeds 4,500 kilograms (9,920 lbs).
2. on both the truck and the towed trailer if:
* the truck's actual weight, registered gross weight or gross vehicle weight rating exceeds 4,500 kilograms, or
* the actual weight of the truck, when added to the actual weight of the towed trailer or trailers exceeds 4,500 kilograms, or
* the gross vehicle weight rating of the truck, when added to the gross vehicle weight rating of the towed trailer or trailers exceeds 4,500 kilograms.
3. on a transport trailer converter dolly, whether the dolly is carrying a trailer or not.