Trailer D-ring tie-downs, properly called lashing rings, comprise a steel D-shaped loop -- similar to a belt buckle -- that moves inside a steel hasp which is in turn bolted or screwed to a sturdy substrate. D-rings are usually installed at several locations around the perimeter of a trailer so that straps or chains can be attached between them and the cargo, then stressed to hold the cargo in place. They are available in a variety of sizes, capacities and safe working load ratings.
Determine the number of D-rings required, and their best locations. They must be positioned so that any cargo secured by them is supported equally from all directions, and prevented from both toppling and sliding.
Position the hasp on the trailer bed so that the D-ring falls toward where the load will be placed.
Use screws, coach bolts or nut/bolt/washer assemblies to fasten the D-ring in place. Use a screwdriver to drive the screws, use an electric drill fitted with a pilot bit before installing coach bolts with a socket set, and drill holes sufficient to accept the bolt shanks entirely through the trailer bed if using nut/bolt/washer assemblies.
