All trailer and tie-down manufac-turers quickly point to the weak-link theory of tying down race cars and equipment; that is, the system is only as strong as the weakest link of each connection.

"Your straps may be rated at a certain strength, but if your D-rings or tracks only hold half that amount, that is the rating of the system link," says Paul Craig of Sooner Trailer Manufacturing. "Every component in a system is rated. But if a strap is rated at 5,000 pounds, the D-ring at 6,000 pounds, but the screws of the D-ring attachment 2,000 pounds, the rating of that tie-down strap link will be 2,000 pounds."

Straps, tracks, and D-rings all have ratings, which every installer and user should be aware of. That rating is also affected by the angle of the tie-down strap, which ideally should be in the 25-35 degree range. That provides both forward-and-aft, and to a lesser degree, up-and-down restraint. Also important are the tie-down points of the straps to the car.

"Tie-down points should be to the axle or some fixed point below the suspension," says Brown.

Another system of tying down a car is with over-the-wheel straps. This system can be very easy to use, but it is important that the straps be used correctly. A single strap holding down the wheel is not a good method--wheels can lose air, and when that happens the connection can become very loose, even to the point of the strap falling off the tire. Remember that part about the car falling off the trailer and passing you?

Much better are the use of tire bonnets--straps that hold the tire down along the top and sides. These bonnets combine the simplicity of single-point attachment hooks with the security of both front-and-rear and lateral restraints.

Most Common Mistake
All manufacturers of trailers and tie-down systems have some good stories about tie-down mishaps, but a common theme arose as to how many of the accidents occurred. That theme is of a D-ring pulling out from its screw anchors.

"The quality of a tie-down system often comes down to the quality of the installation, and the number-one mistake we find is when people put small, little lag screws into plywood when installing D-rings or some other attachment. This is done all the time, especially in the floorboards, often of old and weakened plywood," says Galvin of Featherlite.

For those of us who have seen an overmuscled crew member crank down on a strap ratchet, we can imagine a D-ring being yanked right out of its mounting.

Attachment points, such as D-rings and railing systems, should be secured by methods that don't compromise the load ratings of these attachments. This usually means using through-bolts, metal backing plates, and cross-members welded in underneath the floorboards to chassis points. This will ensure that the attachment and its hardware will never be that weak link in the system.

Versatility
Holding down cars and equipment can be a quick, easy, and secure operation. However, it can also be cumbersome and awkward. Once the necessary load and design criteria have been established for your trailer, the easier your system will be to use and the more likely proper tie-down procedures will be followed by the crew.

Like everything else in racing, the quality of tie-down equipment varies. D-rings, for example, are of different strength ratings, can be flush- or recess-mounted, and can be fixed or rotating. Straps can have simple hook ends or safety keepers. Make sure they don't fall off a connection point. Straps themselves can greatly range in their breaking strength.