Trac-Grabbers were installed using the D-ring locking with the full length of Velcro. The rubber part of the product was pulled in tension to determine the maximum holding force. The failure mode for both the car and truck-based models was the slipping of the strap against the Velcro. The onset of initial Velcro stress / slippage was noted based on audible sounds.
The ultimate force recorded is the maximum force exerted at which the strapping system could no longer support the load.
The image at right shows a Trac-Grabber installed on a hydraulic ram to test the strength of the retaining straps. In the following table, “Initial Slippage” refers to the applied force at which the Velcro first began “stretching”, while “Ultimate Max Strength” is the applied force at which the strapping system could no longer support the load.