Have you ever set your ratchet or cam buckle straps as tight as you possibly could only to find them loose when you stop and check them? You knew the straps were tight before you hit the road. You even put a cinch knot under the ratchet or cam and could tell that neither moved. Why do most strap manufacturers, on the back of their packaging, instruct their strap owners to pull over every 20 to 50 miles to check and retighten your straps? Do they know something you don’t?
The simple answer is, “Yes they do.”
Although tie down webbing might look similar there are key differences between the three types of webbing material. To determine which material works best for tie downs we will compare fiber stretch, UV protection, water resistance, break strength, abrasion resistance, and overall safety.
Fiber Stretch
One of the reasons that tie downs become loose is that the webbing will stretch under a load. Polypropylene is a form of plastic and can stretch over 50% while under load. Nylon tends to stretch between 20 to 30% under a 2500-pound load. Polyester stretches only 5 to 15%, making polyester webbing ideal for heavy loads.
UV Protection
Polyester is highly resistant to UV radiation which means it can stand more prolonged exposure to the sun than Nylon or Polypropylene without the material breaking down.
Water Resistance
Water can affect the strength and durability of tie down webbing materials. Polypropylene and Polyester repel water and are more mildew resistant than Nylon which will absorb water. Nylon webbing becomes much weaker when it is wet and will stretch when it is damp or wet. Polyester webbing can be wet and still be a very strong webbing for tie downs.
Break Strength
The break strength of a webbing material is the maximum stress or load that can be applied to the fabric before failure or it breaks. Polypropylene has a break strength of 700 pounds, Nylon is 2,500 to 7,000 pounds and Polyester is 2,000 to 10,000 pounds.
Abrasion Resistance
Tie down webbing that resists abrasion is extremely important in securing your load. Even seemingly minor webbing damage can significantly reduce the capacity of a tie down to hold objects and increase the chance that the tie down will fail during use. Polyester webbing is more resistant to abrasion than Nylon or Polypropylene.
Overall Safety
Keeping your load safe and secure is extremely important. A tie down must be able to withstand UV radiation, water, and abrasion as well as have a high break strength and a minimal amount of fiber stretch. Using stretchy tie down webbing can cause damage because the stretchy strap lacks the tension needed to keep the load secure. Abraded webbing can increase the chance that the tie down will fail. When comparing overall safety of tie down materials, Polyester webbing is the clear winner.
Tie Down Webbing Comparison
| Tie Down Property | Polypropylene | Nylon | Polyester |
|---|---|---|---|
| Overall Safety | Poor | Fair | Excellent |
| UV Protection | Good | Good | Excellent |
| Water Resistant | Excellent | Fair | Excellent |
| Break Strength (subject to change) | Poor 700 lbs. | Good 2,500 – 7,000 lbs | Excellent 2,000 – 10,000 lbs. |
| Abrasion Resistance | Poor | Fair | Excellent |
| Fiber Stretch | Poor 50% | Fair 20%-30% | Excellent 5%-15% |
The Clear Choice
Polyester webbing is the best material for your tie down straps. Its resistance against abrasion, UV rays, and water make it a better choice for tie-downs than other webbing materials. It is also mildew resistant which makes it an excellent option for snowmobiles and watercraft. The combination of strength and resistance to stretching and abrasion make it ideal for a strong durable tie-down strap.
Bottom Line
Polyester is more expensive than nylon and this is why most tie-down companies have switched to lower quality nylon for their webbing. ShockStraps use 3,800 pound polyester webbing instead of lower cost nylon so our ShockStrap, and not our webbing, does all the stretching. It’s the reason we don’t have customers calling us to say our hooks are coming off of their load or that their straps are coming loose when traveling down the road.