Answering the common buyer question, these adapters convert square gooseneck trailers to a 2″ kingpin or compatible 5th-wheel rail system so you can tow with an existing 5th-wheel hitch. They’re ideal for truck owners who want a quick, at-home upgrade without a full hitch install. The best fit depends on your trailer tube size, desired load, and how easily you want to install. The following picks are tailored for heavy hauling, simple bolt-on setups, and compatibility with standard 5th-wheel rails.
| Product | Tube Type | Capacity | Best For |
|---|---|---|---|
| FlexHitch 30K Lbs GTW Gooseneck to 5th Wheel King Pin Adapter | 4″ Square | 30,000 lbs GTW | Heavy loads on square-tube goosenecks |
| springcraze Kingpin to Fifth Wheel Hitch Adapter | 4″ Square | 30,000 lbs | Adjustable height, wide compatibility |
| TOWGUARD Fifth Wheel to Gooseneck Adapter | 4″ Round / 2″ Kingpin (adapter) | 30,000 lbs | Versatile 5th wheel to gooseneck pairing |
| CURT 16210 X5 Gooseneck to 5th Wheel Adapter | Industry-base rails | 20,000 lbs | CURT rail systems compatibility |
| Stegewop Gooseneck Adapter Hitch | 4″ Gooseneck to 2-5/16″ Ball | 30,000 lbs | Adjustable height, gooseneck compatibility |
FlexHitch 30K Lbs GTW Gooseneck to 5th Wheel King Pin Adapter
Best for: Heavy-duty square-tube gooseneck trailers needing a robust 5th-wheel tow interface. This adapter converts a 4″ square gooseneck tube to a standard 2″ kingpin, enabling a seamless connection with most 5th-wheel hitches. It’s designed for up to 30,000 lbs GTW and 4,500 lbs tongue weight, making it suitable for large equipment, farm gear, and construction materials.
- Easy bolt-on installation with common hand tools; no welding or modifications required.
- Reinforced rib design for improved strength and wobble resistance.
Best for: truck owners who want a straightforward upgrade at home and work with 4″ square tubes. Caution: verify your hitch and trailer exact interface to ensure full compatibility with your current 5th-wheeI system.
springcraze Kingpin to Fifth Wheel Hitch Adapter
Best for: Users needing adjustable installation height and a straightforward 4″ square to 2″ kingpin connection. This adapter supports up to 30,000 lbs and includes four reinforcing ribs for added strength, making it a solid choice for heavy-duty trailers undergoing frequent changes in connect height.
- Extra-long 29″ tube length expands compatibility with various gooseneck and hitch configurations.
- No cutting or welding required; simple 15-minute installation with basic tools.
Best for: fleets or rural users who value height adjustability and quick swaps between gooseneck and 5th-wheel towing. Caution: ensure your trailer’s gooseneck geometry matches the outer tube assembly for proper fit.
TOWGUARD Fifth Wheel to Gooseneck Adapter
Best for: Campers, trailers, and tractors that require seamless 5th-wheel to gooseneck transitions without a full new hitch system. It uses a 4″ round tube and a 2″ kingpin, with a high-capacity 30,000 lbs rating to handle heavy hauls.
- Upgraded reinforcing ribs provide additional durability over basic adapters.
- 26″ length and 4 rib design help prevent flexing during towing.
Best for: practical versatility if your setup changes often between gooseneck and 5th-wheel configurations. Caution: verify that your rails and 5th-wheel hitch are compatible with the adapter’s mounting pattern.
CURT 16210 X5 Gooseneck to 5th Wheel Adapter
Best for: CURT users needing compatibility with industry-standard 5th wheel rails while towing gooseneck trailers. This adapter is rated for up to 20,000 lbs gross trailer weight and fits standard rails for easy installation with compatible trucks.
- Converts CURT double-lock gooseneck hitches to 5th-wheel rails for flexible towing options.
- Industry-standard rails ensure straightforward mounting with CURT and competing 5th wheels.
Better for: users who already own CURT rail systems and want reliable integration without buying a new hitch. Caution: rated to 20,000 lbs, which is lower than some other options—plan capacity accordingly.
Gooseneck Ball to Fifth Wheel Adapter (Springcraze)
Best for: Users needing a heavy-duty 30,000 lbs capacity with an elevated 1.5″ lift, suitable for challenging towing conditions. This adapter uses a 2″ kingpin and 2-5/16″ gooseneck ball to support mixed hitch configurations.
- Powder-coated and phosphate-treated finish provides rust protection in harsh environments.
- 1.5″ lift improves ground clearance for certain trailers and hitches.
Choose this if you require higher ground clearance and strong corrosion protection. Caution: verify that the 1.5″ lift does not interfere with your trailer clearance or hitch alignment.
Buying Guide
What should you check before buying?
Compatibility: Confirm tube size (4″ square vs 4″ round), kingpin size (2″), and whether the adapter fits your 5th-wheel base rails or kingpin interface. Check the trailer and hitch manufacturer recommendations to avoid mismatches.
Load capacity and safety
Look for adapters rated near the maximum weight you will tow. Higher capacity typically reduces risk of wobble or failure in heavy-duty applications. Verify tongue weight ratings to ensure compatibility with your hitch system.
Installation considerations
Bolt-on solutions save time and avoid welding. Some adapters provide longer tubes or reinforcing ribs for improved strength. Consider whether you prefer adjustable height or fixed height, and whether the installation tools you have match the required process.
Compatibility with existing brands
Some adapters emphasize compatibility with CURT, while others advertise universal rails. If you already own brand-specific rails or hitches, choosing a matching adapter can simplify installation and reliability.
Practical use cases
These adapters are best for equipment haulers, construction fleets, and RV setups where a gooseneck trailer needs to be towed by a 5th-wheel hitch. For campers and farmers, the right adapter reduces the need for a full hitch replacement while maintaining towing stability.
FAQ
- Can I install these adapters myself? Yes. Most listed options are bolt-on with basic tools and do not require welding.
- Do all adapters support 30,000 lbs? Not all. Some are rated up to 20,000 lbs; check the specific product rating before purchasing.
- Will these adapters fit my specific 5th wheel rails? Many are compatible with standard rails, but verify the rail pattern and brand compatibility for your truck.
- Is a higher lift always better? Higher lift can improve clearance in some setups, but may affect hitch alignment and approach angles. Confirm fit with your trailer configuration.
- Are there safety concerns with using an adapter? Ensure the adapter is rated for your load, installed correctly, and regularly inspected for wear or damage to maintain safe towing.