Steel Tarps is a common term used to describe a Flatbed Tarp sized and configured to cover smaller height loads that are usually heavy. 12' wide steel tarps are also are also commonly referred to as 2' drop tarps and the 16' wide version as 4' drop tarps. Lumber Tarps are Flatbed Truck Tarps made to cover cargo and protect it from the elements, including rain, snow, and any debris that might be on the road. Lumber Tarps are typically made of vinyl, either 18 oz or 14 oz, and many have a drop-flap to cover the back of the load.