Which vehicles are prohibited from using a road sign-posted like this?

The sign indicates a weight restriction based on axle weight, specifically that vehicles with a permissible axle weight exceeding 2 tons are prohibited.

The correct combination of answers includes:

1. Vehicles with an actual axle weight exceeding 2 tons.
2. Vehicles with a permissible axle weight exceeding 2 tons.

This means any vehicle that exceeds this threshold, whether it is the actual weight or the allowable weight as defined by the vehicle's specifications, cannot use the road.

The third choice, regarding permissible total weight not exceeding 2 tons, is incorrect because it does not pertain to the axle weight restriction outlined by the sign. Under German traffic laws, it is crucial to differentiate between axle weight and total weight since the sign specifically regulates axle weight to ensure road safety and infrastructure protection.