If you haul materials like sheet metal or dirt around to different work sites, then you can benefit from a dump trailer. It makes it easy to haul and unload all sorts of materials. You can buy one with confidence too by utilizing these tips. Choose Appropriate Size There are a lot of different sizes for dump trailers today. Some are 20 feet long, and then others are more compact. The size you get ultimately depends on the material quantity that you plan on hauling on a regular basis.