The chains that are attached to the trailer tongue with hooks on their free ends. These chains keep the trailer connected to the tow vehicle should the coupler or hitch ball detach from the tow vehicle. Safety chains must be secured every time you tow.
Safety chains are a requirement and should be crossed under the tongue of the trailer so that the tongue will not drop to the road if it becomes separated from the hitch. Always leave enough slack so you can turn. Never allow the safety chains to drag on the ground and never attach the safety chains to the bumper. Trailer Classification: Safety Chain Breaking Force-Minimum Class 1: 2000 lbs (8.9 kN) Class 2: 3500 lbs (15.6 kN) Class 3: 5000 lbs (22.2 kN) Class 4: The strength rating of each length of safety chain or its equivalent and its attachments shall be equal to or exceed in minimum breaking force the GVWR of the trailer.
Legally mandated chains that connect the trailer to the tow vehicle as a safety measure in case the coupler detaches.