The B&W Turnoverball GNRK1257 is the under-bed gooseneck hitch for 2007-2021 Toyota Tundra Trucks, and it is the product that made B&W. Everything that carries load lives underneath the bed. The only change to the bed floor is one 4" round hole for the receiver, and the ball itself turns over and stows in that receiver when you are done towing, so the bed goes back to being a bed. Rated 30,000 lb gross trailer weight and 7,500 lb vertical tongue weight with the included 2-5/16" gooseneck ball, and never more than your own truck's tow and weight ratings. The brackets in this kit are cut for this truck platform, so the side plates land on frame holes that are already there with no drilling and no welding. B&W ships the GNRK1257 as two boxes, the GNRM1257 mounting kit and the GNRC1256 center section, and both have to arrive before the hitch can go in.
What's Included:
Turnoverball center section with machined receiver socket
2-5/16" solid machined gooseneck ball, stows inverted in the receiver
5/8" steel locking pin with spring loaded latch handle
Two spring loaded safety chain u-bolts
Vehicle specific under-bed mounting kit and brackets for 2007-2021 Toyota Tundra
Frame hardware pack
B&W installation instructions
Shipped as two boxes, GNRM1257 at about 51 lb and GNRC1256 at about 35 lb
Features
A Hitch When You Need It, a Level Bed When You Do Not This is the feature the whole product is named for. A spring loaded handle in the wheel well is attached to a 5/8" steel locking pin that passes all the way through the ball. Pull the handle toward you and rotate it slightly left and the pin locks out, which lets you lift the ball out, turn it over and drop it back into the same receiver upside down. The bed goes flat, and the ball is stored exactly where you need it next time rather than rolling around in a toolbox. Rotate or push the handle right and the spring pops the latch back into place.
Square Post in a Round Socket Most gooseneck hitches use a round post in a round socket. B&W uses a square post in a round socket, and the reasoning is practical. Only the four rounded corners of the post touch the socket, so the fit is tight enough to tow without rattle but the open round socket still leaves dirt somewhere to go instead of packing solid. The latch pin holes line up in every orientation, and the square base is what keeps a Companion fifth wheel head or a 4" extender aligned with the truck instead of free to rotate.
Only a 4" Hole in the Bed, No Welding and No Drilling The under-bed frame carries the load, so the only thing that happens to your bed sheet is a single 4" round hole for the receiver. The bed stays on the truck, nothing gets welded, and the brackets bolt to holes that are already in the truck frame. Everything below the bed floor is out of sight once the ball is stowed.
Brackets Cut for 2007-2021 Toyota Tundra, Not a Universal Bar The mounting kit in this hitch is designed around one truck platform. The side plates pick up existing frame holes in the right places, the crossmember sits at the right height for that frame, and the receiver lands where the bed hole wants to be. That is why B&W builds dozens of Turnoverball part numbers instead of one adjustable set of rails, and it is the difference between an install measured in hours and one measured in a weekend.
Rated 30,000 lb gross trailer weight and 7,500 lb vertical tongue weight with the 2-5/16" gooseneck ball Capacity on a gooseneck depends on which ball is in the socket, so the number always carries the ball with it. With the 2-5/16" gooseneck ball supplied in this kit the rating is 30,000 lb gross trailer weight and 7,500 lb vertical tongue weight. B&W's own position, printed in the Turnoverball owner's manual, is that the hitch is rated to tow what your truck is rated to tow. Look up your truck's GVWR, GCWR and maximum tow rating before you load a trailer, and treat the hitch numbers as a ceiling you work under rather than a target.
Accessory Compatibility Is Restricted on This Model The Turnoverball socket normally takes B&W's whole accessory range, but B&W calls out this application specifically: only GNXA4585 and the RVK3500 Companion with the special post work with this hitch. Do not assume a standard Companion post or the general purpose extender will drop in. Check the part number against B&W's list before you buy a fifth wheel head for this truck.
Spring Loaded Safety Chain U-Bolts Two safety chain u-bolts are built into the frame and sit down in the lower corrugation of the bed wherever the truck allows it. They are spring loaded, so with nothing hooked to them they drop flush and the bed floor stays usable. Lift the top of the u-bolt to hook a chain, and leave only enough slack for full turning, since excess slack is what stops chains doing their job if the hitch connection ever fails.
Made in the USA, Built by B&W in Humboldt, Kansas The hitch is manufactured in B&W's own plant in Humboldt, Kansas, from American steel, by a workforce that owns the company. It is tested to SAE J2638, the gooseneck and fifth wheel standard, with B&W's stricter internal rule that one sample has to pass all three 300,000 cycle dynamic tests and then the six static tests as well. It carries B&W's Lifetime Exclusive Limited Warranty.
Fitment & Compatibility
Years
Make
Model
Bed
2007-2021
Toyota
Tundra
● Standard
Fit guidance: B&W lists this kit as fitting 2007-2021 Toyota Tundra Trucks. Only Accessories GNXA4585 and RVK3500 with special post work with this hitch The kit arrives as two boxes, GNRM1257 at about 51 lb, GNRC1256 at about 35 lb, so check both have been delivered before you book the install. Bed length, cab configuration and turning clearance still matter: measure from the ball to the cab and from the trailer coupler to the widest point of the trailer nose before towing, and use B&W's 4" extender or Extend-A-Goose coupler if you need more room. B&W's own position, printed in the Turnoverball owner's manual, is that the hitch is rated to tow what your truck is rated to tow. Look up your truck's GVWR, GCWR and maximum tow rating before you load a trailer, and treat the hitch numbers as a ceiling you work under rather than a target.
Specifications
Model: Turnoverball GNRK1257
B&W Part Number: GNRK1257
Hitch Type: Under-bed gooseneck, turnover ball
Fits: 2007-2021 Toyota Tundra Trucks
Gooseneck Ball Included: 2-5/16", solid machined, stows inverted in the receiver
Gross Trailer Weight: 30,000 lb with the 2-5/16" ball, and not more than your truck's rating
Vertical Tongue Weight: 7,500 lb with the 2-5/16" ball, and not more than your truck's rating
Ball for Loads Over 30,000 lb: B&W 3" gooseneck ball GNXA2025, sold separately
Latch: Spring loaded handle, 5/8" steel locking pin through the ball
Bed Modification: 4" round hole in the bed floor
Frame Attachment: Bolts to existing frame holes, no drilling, no welding
Safety Chain U-Bolts: Two, spring loaded, sit flush when not in use
Finish: Powder coat
Fifth Wheel Upgrade: Restricted, see the fitment note
Testing Standard: SAE J2638 for gooseneck and fifth wheel hitches
Shipping Weight: About 84 lb
Shipped As: Two boxes, GNRM1257 at about 51 lb and GNRC1256 at about 35 lb
UPC: 843233004601
Country of Origin: USA, built by B&W in Humboldt, Kansas
Warranty: B&W Lifetime Exclusive Limited Warranty
Installation
Type: Bolt-in under the bed to existing frame holes, no drilling and no welding, plus one 4" round hole cut in the bed floor · Time: About 2 to 4 hours for most installers · Tools: Socket set and torque wrench, 4" hole saw, drill, measuring tape, marker; a floor jack or a second person to hold the frame up · Difficulty: Intermediate, DIY-friendly with normal hand tools
The under-bed frame goes up against the truck frame first, bolted to holes that are already in the frame. With the frame in place, mark and cut the single 4" round hole in the bed floor for the receiver, drop the center section in and torque everything to the values in the printed instructions. Check that the latch pin passes fully through the ball and that the handle in the wheel well is reachable before you tow. Both boxes, GNRM1257 and GNRC1256, have to be on hand before you start. A spray-in bed liner can go on before or after; doing it after has the advantage of sealing the cut edge of the hole.
Watch the installation walkthrough:
Resources
Everything you need for your B&W Turnoverball Gooseneck Hitch, 2007-2021 Toyota Tundra, 2-5/16" Ball, in one place.
Warranty. B&W covers this product under its Lifetime Exclusive Limited Warranty. B&W's published terms cover defects in material or workmanship for the original consumer purchaser, for as long as that purchaser owns the product, with B&W choosing to replace the product or, at its option, repair it or refund the purchase price. Installation, removal and shipping costs are not covered, and normal wear, finish aging and damage from accident or misuse fall outside it. A return authorization from B&W is required before sending anything back, on 800-248-6564. B&W does not authorize dealers or distributors to create any other warranty on its products, so the terms above are B&W's own and are described here rather than extended by us.
Free shipping. This item ships free to the lower 48 states. Because it is an oversized item, it ships by freight and typically arrives in 3 to 7 business days.
Inspect on delivery. Please inspect the packaging before signing. If you see any damage, note it on the delivery receipt and contact us right away, and we will make it right.
About B&W Trailer Hitches
B&W Trailer Hitches started in a Humboldt, Kansas garage in 1987, with two men and an idea. Roger Baker and Joe Works, the B and the W, were building custom truck beds when they got tired of the one thing every gooseneck customer complained about: a ball welded permanently into the bed, in the way every day of the year for the few days a year it was actually towing. They designed a hitch that mounted underneath the bed and a ball that turned over and stowed in its own receiver, and the Turnoverball Gooseneck Hitch was born. A few years later the same under-bed mounting system became the single-point Companion fifth wheel hitch, which is why a Turnoverball socket still accepts a Companion today.
Everything B&W sells is still made in Humboldt. Roger retired in 1999, and in 2007 Joe began transferring ownership of the company to its employees, so the roughly 600 people working in the plant today are also its owners. They buy American steel on purpose and say why: the sheet steel comes out of Burns Harbor, Indiana, and the round bar that becomes the gooseneck ball is drawn at a mill in Norfolk, Nebraska, because when the strength of a piece of steel is the only thing between a truck and a loose trailer, B&W wants a mill it can hold to a specification.
Their testing story is worth knowing before you compare hitches on price. SAE J2638 is the performance standard for gooseneck and fifth wheel hitches, and B&W is blunt that it is only a recommended practice, not a legal requirement to sell one. The standard allows a manufacturer to use a fresh sample for each of its nine tests. B&W's own engineering requirement is stricter: a single hitch has to survive all three 300,000 cycle dynamic tests and then still pass the six static tests, because, as their director of engineering puts it, an accident rarely happens when a hitch is brand new, it happens after years of wear from the road.
Prestige Truck is an authorized B&W dealer. Every hitch we ship is new, in the factory carton, and covered by B&W's Lifetime Exclusive Limited Warranty direct from Humboldt.
B&W Turnoverball Maintenance
B&W's short maintenance guide for the Turnoverball. It covers greasing the four corners of the square post, keeping the latch spring clean by popping the handle a few times, and what to do about a ball that has started to stick.
Two minutes here is what keeps a seized ball from becoming a job.
From Steel To Hitch In 60 Seconds
A timelapse ride through B&W's Humboldt plant as American steel becomes a finished hitch: laser cutting, forming, robotic welding, powder coat and assembly.
Every product B&W sells takes this same route through the same building, built by the employee-owners who stand behind it.
Trailer Tires Matter
What B&W wants every hauler to know about trailer tires: load range, age, and pressure, and how each one changes how a trailer behaves behind your truck.
Tire trouble is the most common roadside failure in towing, and most of it is preventable at the walk-around.
Frequently Asked Questions
Straight answers on specs, fit and support
Will the GNRK1257 fit my truck?
B&W lists this kit for 2007-2021 Toyota Tundra Trucks. Only Accessories GNXA4585 and RVK3500 with special post work with this hitch Check the year, make and model table on this page against your truck before ordering. B&W builds dozens of Turnoverball part numbers precisely because the brackets are cut for one platform, so a kit for a neighboring year or a different cab or frame will not simply bolt on.
Why did only one box arrive?
Because this hitch ships as two. B&W splits the GNRK1257 into the GNRM1257 mounting kit at about 51 lb and the GNRC1256 center section at about 35 lb. Both are needed to complete the hitch, and they can travel separately and land on different days. If one has not shown up, contact us before you book installation time.
How much can I actually tow with it?
With the 2-5/16" gooseneck ball supplied in this kit the hitch is rated at 30,000 lb gross trailer weight and 7,500 lb vertical tongue weight. That is the hitch ceiling, not your ceiling. B&W's own position, printed in the Turnoverball owner's manual, is that the hitch is rated to tow what your truck is rated to tow. Look up your truck's GVWR, GCWR and maximum tow rating before you load a trailer, and treat the hitch numbers as a ceiling you work under rather than a target. B&W also recommends that your vertical tow weight rating be no more than 25 percent of your truck's maximum tow rating.
Can I add a fifth wheel hitch later?
Only with the right parts. B&W calls this application out specifically: only GNXA4585 and the RVK3500 Companion with the special post work with this hitch. Check the part number against B&W's list before buying a fifth wheel head or an extender for this truck, because the general purpose accessories do not all fit here.
Do I need to grease it, and what if the ball seizes?
Apply white lithium grease to the four corners of the square post as needed. The round socket is open at the bottom so dirt has somewhere to go rather than packing in, but grease is still what keeps the ball moving freely. If a neglected ball does seize, soak it with penetrating oil for a day or two and try light taps around the ball with a hammer. B&W is explicit that you must not use heat to free it, because heating the metal changes its temper and its strength.
Will it work with a lift or with air bags?
A suspension lift is fine. A body lift is not, because the hitch depends on the distance between the bed and the frame staying as the factory set it, and a body lift separates exactly those two things. On air bags, B&W says that to the best of their knowledge Air Lift and Firestone build systems compatible with the Turnoverball on 2005 and newer trucks. Check with the airbag manufacturer for your specific truck.
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