Final answer:
The earliest and best way to recognize a trailer skid is by seeing it in your mirrors, a crucial safety measure while driving on the highway. Observing the trailer's movement can also indicate if it's heavily loaded or nearly empty, with more bounce suggesting it is nearly empty.
Step-by-step explanation:
The earliest and best way to recognize that the trailer has started to skid is by seeing it in your mirrors. This answer applies significantly when you're driving or managing a vehicle on the highway. It is crucial for safety to keep a vigilant watch on the trailer through your mirrors to observe any irregular movements or skidding. If you notice that the trailer is bouncing up and down slowly, this could indicate that the trailer is nearly empty. A heavily loaded trailer would have less bounce due to the weight pressing down on the suspension.