Cargo strap purchase tips

Tie-down or cargo web straps (officially called securement devices) have become ubiquitous, increasingly replacing chains to secure cargo and light equipment loads, such as large round bales, seed corn, pesticides, and even mowing tractors. Chains are still required to secure heavier loads like sprayers, tractors, and construction equipment.

While straps provide a quick and easy way to secure loads, they have been abused or their holding capacity often overestimated, says Fred Whitford of Purdue University. Whitford formed a team of experts to produce the ultimate guide to securing loads, Securing the Load (PPP-75), found online at extension.purdue.edu/extmedia.

“Almost without exception, cargo falling off a truck or trailer costs you money,” Whitford says. “But if your cargo falls into traffic and causes an accident, you face legal repercussions due to personal injury, environmental contamination, or property damage. If you are found negligent, your insurance company can refuse payment in certain situations.” Whitford urges scrutiny of any web straps before purchase and also evaluation of the condition of straps in use.

Sizing Up Straps

The fabric used to create cargo straps is 100% high-tenacity polyester webbing. The key determining factor of a strap’s quality and capacity is its listed working load limit (WLL). Either printed on a tag sewn into the end of the strap or printed on the webbing itself, the WLL reveals the maximum weight a strap can support with regular day-today use without becoming damaged.

WLL is generally calculated as one-third of the breaking strength of the strap and its tightening mechanism. For example, a tie-down with 7,500-pound breaking strength has a WLL of about 2,500 pounds.

Breaking strength aside, the WLL is the ultimate guide to a strap’s ability. If the strap doesn’t list a WLL, don’t buy it.

That being said, straps sometimes are sold listing an inaccurate WLL. Low quality straps can tear or snap before reaching their WLL. With that in mind, stick to well-known manufacturer names when buying straps.

Strength of Tightening Mechanisms

Generally, cargo straps are sold with different methods of tightening the strap on the load. Those mechanisms include:

• Lashing straps. This simple tightening mechanism is a lightweight slip catch or gator-clip design. They are the lightest-duty tightening mechanism on the market, often offering only a 100-pound WLL.
• Cam buckle straps. More heavy duty than lashing strap catches, a cam buckle is quicker to tighten and release than a ratchet strap but has a 500-pound WLL.
• Ratchet straps. The preferred strap mechanism on farms, the ratchet strap employs hardware that can create a tighter and more secure restraint. Depending on their widths and grade, ratchet straps can have WLL up to 5,000 to 6,000 pounds.

Securement Ends

Strap quality, ease of use, and WLL are also determined by the ends placed on the strap. End types include:

• S-hook. These are the most common type of ends on the market. Their capacity varies greatly by the quality of the strap manufacturing, and that is reflected in the WLL.
• Snap hook. Similar to S-hooks, these ends feature a latch that snaps closed around the tiedown point to provide a more secure fitting.
• Flat hook. These low-profile and versatile designs go over the rub rail on flatbed trailers, slipping over flat bars to secure the strap.
• J-hook. Also known as wire hooks, J-hooks are typically used at one end of a ratchet strap to grip into an anchor point. They are generally the strongest of the hook types.
• Chain ends with chain hooks. These extra heavy-duty strap ends offered the highest capacity loading on straps.

Usage Rules

Follow these guidelines when using straps to ensure a solidly secured load and increase strap life.

• Don’t be stingy with straps. This is easily the most ignored guideline, Whitfold warns. Use more than you need so if a strap breaks or a tightening mechanism fails, you are covered.
• Never knot straps, particularly ratchet straps, as doing so cuts their strength 15% to 20%.
• Lubricate the tightening mechanism with a silicone spray or other spray lubricant (like WD-40).
• Don’t overtighten straps as this both damages the straps and can damage the cargo it is securing.
• Check and then recheck straps after driving down the road to make sure they are tight enough to keep your load secure. Straps can and do loosen as cargo shifts in transport. 

Limited Life Span

Straps do have a limited life. Frayed webbing, burn defects, excess webbing inside the ratchet, weathering such as sun damage or mold and mildew — all weaken the strength of tie-down straps. On average reputable cargo straps can last three to five years (if used constantly), but only if they are properly stored and not exposed to sharp edges that cause friction or burn area on the webbing. 

Whitford says the U.S. Department of Transportation has established “out-of-service” limits for straps based on the size of the hole or tear in the webbing relative to strap width (see chart below).