A small, inconspicuous door can often be seen on the back of semi-trailers.  Positioned away from standard loading and ...

If you've ever been stuck behind a slow-moving semi-truck with nothing to do, you may find yourself wondering what the little door on the trailer is for.

According to Central California Truck and Trailer Sales, the door on the back of semi-trailers is used for ... ventilation not only protects the cargo, but the drivers who are held responsible ...