Ratchet Straps in the Rain: What to Know

Short answer: yes, you can leave polyester ratchet straps tight overnight in the rain — wet polyester webbing keeps about 95-100% of its rated strength, and the ratchet will hold tension. What fails first is not the webbing but the hardware and the storage: galvanized ratchets rust at scratched contact points, wet webbing stored in a coil grows mildew within 48-72 hours, and temperature swings overnight can drop tension 5-10% on compressible loads.

The rule we give customers at the factory: leaving straps on in the rain overnight is fine, leaving them on for a month is not.

Why polyester survives water and nylon does not

The webbing on almost every ratchet strap sold for cargo use is polyester (PET). Polyester absorbs less than 1% of its own weight in water, and wet polyester retains roughly 95-100% of its dry break strength. Nylon is the opposite: it absorbs 6-8% of its weight, swells, and loses 10-15% of its strength wet — which is why nylon is used for recovery ropes and tow straps that need stretch, not for load restraint.

That is the technical reason "waterproof ratchet straps" is a category that does not really exist. You do not need a waterproof strap. You need a polyester strap, a coated hook, and a habit of drying it before storage.

• Polyester (PET) — <1%, 95-100% of dry, Ratchet straps, tie downs, winch straps

• Nylon (PA) — 6-8%, 85-90% of dry, Tow straps, recovery ropes, kinetic ropes

• Polypropylene — <0.1%, 95-100% of dry, Light-duty cam buckle straps, ropes

The four things that actually degrade overnight

1. Rust at scratched contact points. A zinc or galvanized coating protects the ratchet body and hooks until it is scratched — and hooks get scratched constantly against bed rails and D-rings. Once bare steel is exposed, overnight rain plus morning dew starts surface rust, and rust in the pawl-and-gear interface is what makes a ratchet feel stiff or refuse to release a month later. No strap has ever lost its rating from one wet night, but plenty of ratchets have seized from a season of it.

2. Mildew in coiled webbing. Water sitting between the layers of a rolled strap cannot evaporate. In warm weather mildew colonises the weave in 48-72 hours and leaves a permanent musty smell plus a rough, abrasive surface that accelerates internal abrasion. This is the single most common way a wet strap gets destroyed — not by the rain, but by being coiled wet.

3. Tension loss from temperature, not water. Webbing contracts in cold and expands in heat. A strap tensioned at 30°C in the afternoon and left out at 8°C overnight will read noticeably looser in the morning — typically 5-10% on a compressible load such as cardboard, lumber or a tarped pallet. The ratchet did not slip; the geometry changed. Re-tension before you drive.

4. Cargo that holds water against the strap. A tarped load is the worst case: the tarp pools water, the strap passes through the puddle, and the webbing stays saturated for hours while under load. If you must leave a tarped load out, route straps so water runs off rather than along the webbing.

Overnight checklist

• Truck parked, uncovered load, one rainy night — Yes, Check tension, dry the ratchet, drive

• Tarped load with water pooling on the tarp — Yes, but re-route straps, Drain the tarp, re-tension, dry webbing

• Load parked for a week or more — No — release tension, Wipe down, store dry and loose

• Sub-zero night, compressible cargo — Yes, Re-tension before driving; expect 5-10% loss

• Straps left on an empty trailer — No, Coil loosely and hang to dry

How to dry and store straps properly

Unroll the strap fully and hang it in moving air — a garage with a fan is better than a hot shed, because heat alone bakes moisture into the weave. Never store webbing in a closed plastic bag while damp. Once dry, coil loosely and keep straps out of direct sun: ultraviolet exposure is a far bigger long-term threat than water, degrading polyester at roughly 1% strength per month of continuous outdoor exposure.

For the full inspection routine between trips, see our guide to working load limit vs break strength and when to replace tie down straps.

Frequently asked questions

Are ratchet straps waterproof? No strap is fully waterproof in the sense of being sealed. Polyester webbing is water-resistant and keeps 95-100% of its strength when wet, and galvanized hardware resists corrosion, but prolonged submersion or storage in standing water will damage stitching and seize the ratchet.

Can I leave ratchet straps on my cargo in the rain overnight? Yes. One or two wet nights will not reduce the working load limit of a polyester strap. Check tension in the morning, especially on compressible loads, and dry the strap before storing it.

Will rain make my ratchet strap weaker? Not meaningfully while it is wet. The permanent damage comes from storage: webbing coiled wet develops mildew, and rust in the pawl and gear is what actually retires the strap.

Can ratchet straps rust? The webbing cannot rust, but the ratchet body, springs and hooks are steel. Galvanized or zinc-plated hardware resists rust until the coating is scratched; inspect hooks and the ratchet housing and touch up or replace anything showing orange-brown corrosion.

How often should I re-tension straps in wet weather? Check after the first 15-30 minutes of driving and again every 100-150 miles, which is the same interval FMCSA recommends for any load. Wet webbing stretches slightly more than dry, so the first check matters most.

Need straps that survive real weather?

We manufacture polyester ratchet straps with galvanized hardware, UV-stabilised webbing and GS / TÜV certified ratings for European and North American buyers — from 1-inch 800 lbs break strength up to 4-inch 10,000 lbs assemblies. Request a quote or browse ratchet tie down straps for standard sizes, and see our FAQ for MOQ, samples and lead times.