The nominal load-carrying weight of a winch strap is typically based on industry standards and guidelines, as well as the specifications provided by the manufacturer. The primary standards and references that dictate load-carrying capacities and safety factors for winch straps include:

Web Sling and Tie Down Association (WSTDA): The WSTDA is a prominent organization that develops standards and guidelines for web slings, tie-downs, and related equipment, including winch straps. Their standards, such as the WSTDA-T-1, provide detailed information on the working load limits (WLL), safety factors, and testing procedures for various types of straps, including winch straps.

Federal Motor Carrier Safety Administration (FMCSA): In the United States, the FMCSA has established regulations and guidelines for cargo securement in the transportation industry. These regulations include specific requirements for securing cargo with devices like winch straps. The FMCSA's rules dictate the minimum safety standards that must be followed by commercial motor carriers.

National Association of Chain Manufacturers (NACM): NACM develops standards for chains and related products. While primarily focused on chains, their standards also cover certain aspects of tie-down equipment, including load-carrying capacities and safety factors.

Manufacturer's Specifications: Manufacturers of winch straps provide specifications and guidelines for their specific products. This includes information on load capacity, safety factors, and recommended usage. It's essential to follow the manufacturer's recommendations for a particular winch strap to ensure safe and effective usage.

Other Industry Standards: Depending on the region and industry, there may be additional standards and regulations governing the use of winch straps. It's important to be aware of and adhere to these standards to ensure compliance and safety.

Load-carrying capacities for winch straps are typically expressed as Working Load Limits (WLL). The WLL represents the maximum load that a winch strap is rated to safely secure. It is important to note that the WLL takes into account a safety factor to provide a margin of safety, ensuring that the strap can handle unexpected loads and variations in conditions.