When the front trailer supports are raised and the trailer is resting on the tractor, what should be ensured?

When the front trailer supports are raised and the trailer is resting on the tractor, it is crucial to ensure that there is sufficient clearance between the tractor frame and the landing gear. This clearance is necessary to prevent any interference or damage during operation, especially when turning or maneuvering. If the landing gear is too close to the tractor frame, it can create stress points that lead to deformation or structural failures.

Maintaining proper clearance allows for the free movement of the components while the trailer is in motion, reducing the risk of accidental contact that could result in wear or failure of parts. Ensuring this clearance contributes to overall safety and efficiency in towing operations.

The other options do not address the critical aspect of clearance which directly impacts the physical interaction between the trailer and the tractor.