In just three short lines, Dave Bonta puts a whole scene of exhaustion on the page. We see a dark road at night, and on it a group of men who are "numb" and "borne," meaning carried along rather than walking under their own power. They seem to be in a vehicle, or perhaps simply swept along by circumstance. We aren't told who they are or where they're going.
The clever turn is the last word, "tire." It works in two ways. As a verb, the men are growing tired. As a noun, it points to the tires of whatever carries them, rolling along the road. The title, "Worn down," fits both meanings too: people wearing out, and rubber wearing thin on pavement.
The speaker stays detached, simply observing, and that flat tone adds to the feeling. There's no complaint, only a numbness that matches the men's. The mood is bleak, weary, and quiet, like a long journey at night when everyone has stopped talking and the road just keeps going.