At a Glance
- SKU: KP5G-Q25IP
PRODUCT INFORMATION
Product Details
Gooseneck Coupler Adapter / Fifth Wheel Conversion
Gooseneck to 5th Wheel Trailer Coupler Adapter - 25K - Inner Tube - Square - 25K
Heavy-duty square inner tube adapter that converts a gooseneck trailer coupler to a 2" industry-standard king pin for towing with a fifth wheel hitch.
Part Number: KP5G-Q25IP 4" Square Inner Tube 25,000 lb Rating
Overview
This gooseneck-to-fifth-wheel adapter is designed to replace the inner tube on most standard 4" square gooseneck couplers and provide a 2" industry-standard king pin connection. It is a practical solution for customers who need to tow a gooseneck trailer with a truck already equipped with a fifth wheel hitch.
R&P Service Insight
Coupler adapters like this are most useful when the trailer and truck are set up with different hitch systems. Before ordering, confirm your outer coupler tube size, pin hole diameter, required adjustment range, and trailer capacity.
- Towing Flexibility: Converts a gooseneck trailer connection for use with a fifth wheel hitch.
- Height Control: The 8" vertical adjustment range helps correct trailer attitude and hookup geometry.
- Heavy-Duty Application: Steel construction and a 25,000 lb rating support demanding trailer use.
R&P Knowledge Hub
Compatibility: Fits most standard 4" square outer gooseneck coupler tubes.
Vehicle / System Fit: For gooseneck trailers being towed by trucks equipped with a fifth wheel hitch instead of a bed-mounted gooseneck ball.
Installation Notes: Uses 13/16" pin holes and requires a compatible load-bearing pin such as GCPN-PIN, sold separately.
Performance Insight: Proper trailer height helps improve ride quality, towing stability, and overall trailer-to-truck hookup geometry.
Brand & Fitment Note
Selling Brand: R&P Carriages stocked trailer coupler adapter.
Application Reference: This listing describes trailer-side gooseneck-to-fifth-wheel compatibility where tube size, pin hole size, capacity rating, and adjustment requirements match.
What This Means: This listing is for a gooseneck to fifth wheel inner tube adapter with a 2" king pin connection. It is not presented as a vehicle-specific OEM component.
Before Ordering: Verify measurements, outer tube size, pin diameter, required adjustment range, trailer capacity, and included components before installation.
R&P Repair Insight
Adapter fitment depends on matching the trailer’s existing outer coupler tube and pin setup. A correct fit should slide into the outer tube properly, align with the pin holes, and provide enough vertical adjustment to level the trailer.
- Check Tube Size: Confirm your trailer uses a standard 4" square outer gooseneck coupler tube.
- Check Pin Size: This adapter uses 13/16" pin holes and requires a compatible load-bearing pin.
- Check Trailer Height: The 8" adjustment range should be compared against your tow vehicle and trailer ride height before ordering.
Features
Gooseneck to Fifth Wheel Conversion
Converts a gooseneck trailer coupler connection to a 2" industry-standard king pin for use with a fifth wheel hitch.
4" Square Inner Tube Fit
Designed to replace the inner tube on most standard 4" square outer gooseneck coupler tubes.
8" Vertical Adjustment
Adjustable height range helps level the trailer and improve towing geometry across different truck and trailer combinations.
25,000 lb Rated Construction
Heavy-duty steel construction is rated up to 25,000 lbs and is SAE J2638 compliant.
Specifications
| Specification | Detail |
|---|---|
| Part Number | KP5G-Q25IP |
| Product Type | Gooseneck to fifth wheel inner tube adapter |
| Application | Converts a gooseneck trailer coupler for towing with a fifth wheel hitch |
| King Pin | 2" industry-standard king pin |
| Tube Width | 4" |
| Vertical Adjustment Range | 8" |
| Hole Spacing | 2-11/16" center-to-center |
| Pin Hole Diameter | 13/16" |
| Plate Dimensions | 9-7/8" long x 10" wide |
| Overall Length | 34-3/4" |
| Weight Capacity | 25,000 lbs |
| Compliance | SAE J2638 |
Fitment / Application
| Category | Details |
|---|---|
| Trailer System | Gooseneck trailers being towed by trucks equipped with a fifth wheel hitch |
| Primary Fit | Most standard 4" square outer gooseneck coupler tubes |
| Capacity Application | Trailer-side coupler application rated up to 25,000 lbs |
| Notes | Requires a compatible load-bearing pin such as GCPN-PIN, sold separately. Verify tube size, pin hole diameter, and trailer rating before installation. |
Included Components
| Quantity | Item |
|---|---|
| 1 | Gooseneck to fifth wheel square inner tube adapter with 2" industry-standard king pin |
Verify all specifications, measurements, pin size requirements, coupler tube size, weight rating, vertical adjustment range, and coupler compatibility before installation. Load-bearing pin is sold separately unless otherwise stated.
KP5G-Q25IP gooseneck to fifth wheel adapter, gooseneck trailer coupler adapter, 2 inch king pin adapter, 4 inch square gooseneck inner tube, 25000 lb gooseneck coupler adapter, fifth wheel conversion tube, adjustable gooseneck king pin adapter, SAE J2638 trailer coupler adapter, gooseneck to 5th wheel inner tube adapter
Thank You For Choosing R&P Carriages As Your Online Shopping Source!
Related Parts & Kits
Check fitment, measurements, and kit contents before ordering. Related parts may not be required for your repair.
Looking up part numbers in our catalog…
Your repair list1 item selected
Selected products are added together. Review the cart and verify kit contents to prevent duplicates. Prices and discounts are determined at checkout.
BEHIND THIS LISTING
PHOTOGRAPHY & RESEARCH
Ariah Granados
DIGITAL PRESENTATION & DEVELOPMENT
Ken Martin
ONLINE SALES & QUALITY ASSURANCE
Rayn Fisher
WE’RE HERE TO HELP
Not sure it fits?
Have your SKU or manufacturer part number, photos of the original part and mounting, and any critical measurements ready. Capacity, voltage, or bolt pattern can help too.
815-357-3292 · 270 E Jackson St · Seneca, IL 61360
CUSTOMER REVIEWS
Leave a Google review
Good people. Real trailer work.
Customer feedback summarized from Google and Yellow Pages. Dates are shown where available.
TRAILER PARTSGOOGLE
Ordered trailer repair parts repeatedly; praised fast service, careful packing, and accurate orders.
RV KEYSGOOGLE
Found the correct RV keys at a good price with free shipping; the keys worked as expected.
AXLE & LEAF SPRINGSGOOGLE
Needed an unusual axle and leaf-spring size; the team listened and helped him sort out the fit.
PARTS & SHIPPINGGOOGLE
Praised the OEM and aftermarket selection, discounts, quick shipping, and friendly parts staff.
CUSTOM AXLEGOOGLE
Got the axle he needed right away, set up with a custom spring perch.
WELDINGGOOGLE
Praised the polite staff and quality welding on a project.
GAS STRUTGOOGLE
Replacement struts brought a long-used door back to working order.
CUSTOM TRAILERGOOGLE
Had a trailer built to his needs at a fair price, then found parts for two other trailers in stock.
CUSTOMER SERVICEGOOGLE
Praised the customer service after working with R&P over several years.
GAS SHOCKGOOGLE
Found the gas shock he wanted at a good price with shipping included.
CARGO TIE-DOWNGOOGLE
Received swivel D-rings with backing plates and praised the price, correct order, and service.
PARTS DELIVERYGOOGLE
The right parts arrived the first time, with fast delivery and helpful staff.
PROJECT HELPYELLOW PAGES
Said project advice and prompt shipping helped finish a trailer project.
SHIPPINGYELLOW PAGES
Reported helpful service and fast shipment to Germany.
SUSPENSION KITYELLOW PAGES
Praised a suspension kit, fair pricing, and good parts.
TRAILER CORDYELLOW PAGES
Was pleased with a replacement trailer cord.
SERVICE & PARTSYELLOW PAGES
Noted dependable service and products across repeat visits.
AXLE INSTALLATIONYELLOW PAGES
Said the axle installation fit perfectly and thanked Josh and the crew.
HITCH REPLACEMENTYELLOW PAGES
Praised the crew’s professionalism during a difficult hitch replacement.
PRICE & SERVICEYELLOW PAGES
Liked the product, price, communication, and shipping.
LISTING INFORMATIONYELLOW PAGES
Said the product description explained what would work for the trailer.
PRODUCT & SHIPPINGYELLOW PAGES
Received the item as described with very fast shipping and plans to return.
COMMUNICATION & SHIPPINGYELLOW PAGES
Praised accurate description, quick shipping, and clear communication.
PRICE & PRODUCTYELLOW PAGES
Was happy with the product and its price.
SELLER EXPERIENCEYELLOW PAGES
Called it a pleasure doing business with R&P.
INSTALLATIONYELLOW PAGES
Was pleased with product quality, quick delivery, and an easy installation.
PRODUCTSYELLOW PAGES
Was enthusiastic about the products.
DURABILITYYELLOW PAGES
Was ready to install the product on every trailer they own.
REPEAT CUSTOMERYELLOW PAGES
Expected to buy again after a good experience.
INSTALLED PARTYELLOW PAGES
Reported that the newly installed parts were working perfectly.
REPEAT CUSTOMERYELLOW PAGES
Said things went well, as they had on previous visits.
COMMUNICATION & VALUEYELLOW PAGES
Praised clear communication and fair value.
TRANSACTIONYELLOW PAGES
Said the transaction went as expected.
PRICE & PACKAGINGYELLOW PAGES
Noted good value, careful packing, and fast shipping.
PROFESSIONAL SERVICEYELLOW PAGES
Found the team professional and easy to work with.
COMMUNICATION & SHIPPINGYELLOW PAGES
Praised fast shipping and good communication.
TEAMYELLOW PAGES
Shared appreciation for the owners and their company.
SHIPPINGYELLOW PAGES
Reported prompt shipping and said they would buy again.
CUSTOMER SERVICEYELLOW PAGES
Found R&P easy to deal with.
SERVICEYELLOW PAGES
Praised the people and the service.
FIT & SHIPPINGYELLOW PAGES
Reported a good fit, fair price, accurate listing, and quick shipping.
DELIVERYYELLOW PAGES
Received the order a day early and recommended the seller.
CUSTOM TRAILERYELLOW PAGES
Described a no-hassle, professional custom-trailer purchase.
TRAILER PURCHASEYELLOW PAGES
Praised a new trailer, custom additions, helpful staff, and clear pricing.
HUB COVERSYELLOW PAGES
Found the right hub covers quickly and got helpful maintenance advice.
AXLE HELPYELLOW PAGES
Said R&P helped their company get back on the road after an axle problem.
DUMP TRAILERYELLOW PAGES
Was happy with a dump-trailer purchase after comparing options.
BRAKES, DRUMS & SEALSYELLOW PAGES
Received clear help choosing brake assemblies and bearing seals, followed by fast shipping.
DUMP TRAILERYELLOW PAGES
Found a good deal on a 16-foot dump trailer and planned to return.
FRIENDLY SERVICEYELLOW PAGES
Thanked the staff for their patience and recommended the shop.
Showing 3 of 50
Need help with this part? Send photos, part numbers, and measurements. We’ll help you narrow it down.