CURT 2-5/16 in Trailer Ball Chrome 40039 — 12,000 lb Forged Steel Tow Ball

CURT's 2-5/16-inch chrome trailer ball (model 40039) is a heavy-duty tow ball engineered to safely handle up to 12,000 pounds of gross trailer weight.

Built for demanding towing tasks, this CURT trailer ball combines forged, heat-treated steel with a corrosion-resistant chrome finish and a threaded shank for a secure setup. It’s designed to pair with 2-5/16" couplers and class 5 hitch systems, making it suitable for large trailers, RVs, equipment haulers and other substantial loads when matched with properly rated towing components.

How does this trailer ball deliver the strength needed for heavy towing?

The CURT 40039 is manufactured from hot-forged, heat-treated steel to provide high tensile strength and impact resistance under load. Its 12,000 lb gross trailer weight rating reflects controlled material processing and quality checks performed during production.

• Hot-forged, heat-treated steel construction for durability
• 12,000 lb gross trailer weight rating for heavy trailers
• Tested to U.S. VESC standards to ensure consistent performance

Will this ball fit my coupler and mounting setup?

The ball has a 2-5/16" diameter to match standard 2-5/16" couplers and a 1" shank diameter with a 2-1/4" shank length for secure installation on compatible ball mounts. Fine threads and the included hardware allow a close, reliable connection to your hitch.

• 2-5/16" ball diameter — fits industry-standard 2-5/16" couplers
• 1" shank diameter, 2-1/4" shank length for common mounts
• Zinc-plated hex nut and helical lock washer included for a tight fit

How does the finish protect the ball from weather and wear?

The polished chrome plating provides a barrier against moisture and road contaminants to reduce corrosion and surface wear. This finish keeps the ball looking clean and helps extend service life with routine maintenance.

• Nickel-chrome plating resists rust and road grime
• Smooth surface for easier cleaning and reduced coupling friction
• Protective finish supports long-term reliability with occasional care

What hardware and torque are required for safe installation?

CURT supplies a zinc-plated hex nut and a helical lock washer to secure the ball to the mount. Proper tightening to the specified torque is essential for a strong mechanical joint and safe towing operations.

• Includes zinc-plated hex nut and helical lock washer for secure fastening
• Fine threads help maintain clamp-down under load
• Recommended torque: 250 ft-lb to achieve correct preload on the shank

Who this product is for: The CURT 40039 2-5/16" trailer ball is aimed at drivers who tow heavy trailers, such as dump trailers, toy haulers, dual-axle utility trailers, larger RVs and small boats, and who already have or plan to use class 5 hitch components. Always confirm that the lowest-rated item in your towing system (vehicle hitch, ball mount, trailer coupler) meets or exceeds the 12,000 lb rating before use, and follow manufacturer torque and installation instructions for safe operation.