Adding a Spare Tire Carrier to Your Trailer — A Buyer’s Guide

You’re an hour from home, the trailer is loaded, and one of its tires fails. You have a spare in the back of the truck, but it belongs to the truck: the wheel diameter, bolt pattern, center bore, offset, load capacity, or stud size may be completely different from the trailer’s running gear. Now you have thousands of pounds of equipment sitting on the shoulder of a two-lane road in Owen County while you look for a tire shop willing and equipped to make a roadside call on a Saturday.

A properly selected spare tire carrier, paired with the correct mounted spare, prepares you for that situation. It is not a glamorous trailer upgrade, but it can be one of the most practical additions you make. Light-duty U-bolt carriers can cost roughly $20 to $40, stronger offset tongue carriers commonly run around $90 to $120, and underbody winch or telescoping systems can cost $160 to $300 or more before the wheel, tire, lock, installation labor, or fabrication is added. The important part is choosing a carrier that fits your trailer’s structure, clears every moving component, supports the complete wheel-and-tire assembly, and remains accessible when the trailer is loaded.

Where Does the Carrier Mount?

This is the first decision, and it shapes everything else. The three most common mounting areas are the tongue, a structural rail or upright near the fender, and the deck, frame, or underbody area. The best location depends on the trailer design, the weight of the spare, the available frame geometry, and whether the trailer has a fixed deck, dump body, tilt deck, enclosed body, gooseneck, toolbox, winch, or loading ramps.

Whatever location you choose, the carrier should transfer the spare’s weight into a structural member. Sheet metal, expanded metal, aluminum skin, a thin fender top, or an enclosed trailer’s exterior wall is not automatically strong enough to support a bouncing wheel-and-tire assembly. A spare that weighs 50 to more than 100 pounds can impose much higher dynamic loads when the trailer hits potholes, railroad crossings, gravel roads, or job-site entrances.

Tongue Mount

Tongue-mounted carriers clamp or bolt to an A-frame rail, straight tongue, or other approved structural tongue member. They are common on utility, landscape, boat, car-hauler, and equipment trailers because the spare remains visible, accessible, and outside the load space. An offset or raised carrier can position the tire above and beside the tongue instead of directly in front of the coupler.

The main drawback is congestion. The tongue may already contain the coupler, jack, safety-chain attachments, breakaway switch, breakaway battery, electrical junction box, tongue toolbox, hydraulic pump, tarp hardware, winch equipment, or dump controls. The spare must not restrict access to any of those components. It also needs enough clearance for the tow vehicle’s bumper and tailgate during tight turns, especially on trailers with a short A-frame.

A verified heavy-duty example is the Fulton HDSTC 0101. Fulton specifies that it fits most 4-, 5-, and 6-lug wheels up to 16-1/2 inches and trailer tongues up to 3 inches wide by 5 inches high. Its raised design provides 4-3/4 inches of lift and more than 7 inches of offset. It is zinc-plated and installs with included bolt-on hardware. Depending on the seller, current retail pricing is generally around $90 to $120. Remember that the 16-1/2-inch specification refers to wheel fit, not the complete outside diameter of the mounted tire, so the tire still needs to be measured for clearance.

Tongue mounting also changes tongue weight. A spare mounted forward of the trailer axles normally adds most of its weight to the hitch. That may be helpful on a trailer that is otherwise properly balanced, but it still counts against the tow vehicle’s receiver, hitch, ball mount, coupler, and payload limits. Do not use a spare tire to correct a badly loaded trailer; cargo position should be adjusted first.

Fender Mount

A carrier can sometimes be positioned beside or above a fender, but it should normally attach to the trailer frame, a reinforced side rail, a structural upright, or a factory-designed fender support. Mounting a spare directly through an unsupported fender skin is rarely a good idea. Even a substantial-looking treadplate or stamped steel fender may be designed only as a splash guard, not as a load-bearing bracket.

Before using the fender area, inspect how the fender is attached. Bolt-on fenders, removable drive-over fenders, and lightly supported utility-trailer fenders can flex independently of the main frame. A spare mounted to one of these components may crack the fender, enlarge bolt holes, loosen fasteners, or interfere with tire travel. The carrier must also remain outside the suspension’s full compression path and far enough from the running tire to prevent contact if a spring, equalizer, shackle, or tire fails.

For lighter trailers, a U-bolt-style product can often be installed on a structural rail near the fender rather than on the fender itself. The C.E. Smith 27201 carrier uses 7/16-inch rod construction, mounts to a frame, tongue, or rail up to 3 inches wide, and fits 4- or 5-lug wheels from 8 through 14 inches plus most 15-inch wheels. The related C.E. Smith 27202 package adds a lock and is commonly sold for about $25 to $40. This style is intended for appropriately sized light-duty trailer wheels; it is not a substitute for a fabricated heavy-equipment-trailer mount.

Bed or Frame Rail Mount

Flatbeds, deck-over trailers, equipment trailers, and goosenecks often use a carrier attached to a structural side rail, front bulkhead, gooseneck structure, deck support, or under-deck crossmember. This can keep the spare outside the working deck and reduce interference with cargo. On a heavy trailer, a factory carrier or a bracket designed for that specific frame is usually preferable to a generic light-duty clamp.

Current Diamond C mounting arrangements vary by model and configuration. The GTU Premium Tandem Axle Utility Trailer uses an under-frame spare mount, while current LPX and HDT equipment-trailer configurators provide model-specific spare-mount locations. Current FMAX Fleetneck 2.0 gooseneck models place the spare under the deck and use a winch to raise and lower it. Those factory arrangements are designed around the trailer’s frame, tire package, deck operation, and available clearance, which is difficult to duplicate with a universal bracket.

On a dump or tilt trailer, never choose a mounting location by looking only at the trailer in its lowered position. Raise the dump body or tilt deck through its complete range and inspect the hoist, cylinder, hinges, scissor assembly, hydraulic hoses, wiring, safety prop, ramps, and frame clearance. A carrier attached to the wrong crossmember can block the hoist, trap the spare when the trailer is loaded, or place the tire in the path of the moving deck.

Enclosed cargo trailers may use an interior wall mount, structural exterior mount, rear-frame mount, or underbody carrier. An underbody system keeps the tire out of the cargo area, but it must fit between structural crossmembers and remain clear of the axle, suspension, brake wiring, floor fasteners, plumbing, tanks, stabilizers, steps, and rear departure angle. Ground clearance should be checked with the trailer loaded, not only while it is empty.

The BAL Hide-A-Spare 28217B and 28218B are current telescoping under-frame systems for compatible I-beam towable frames. The 28217B is the recessed version, while the 28218B is the underslung version. BAL specifically warns that these products are not universal and are not intended for motorhomes because of frame-width, ground-clearance, and tire-weight limitations. Typical retail prices are approximately $165 to $260 depending on the model and seller.

Lippert also sells under-chassis winch-style assemblies, including the 159041 71-inch Spare Tire Carrier. The system uses a winch to raise and hold the spare beneath the chassis. Lippert’s current direct price is approximately $259, but the trailer owner still has to verify frame compatibility, tire clearance, mounting structure, crank access, and the ability to lower the spare safely at the roadside.

Bolt-On vs. Weld-On: Which One Do You Actually Need?

Most trailer owners should begin with a purpose-built bolt-on carrier that clearly lists compatible frame dimensions, wheel sizes, bolt patterns, and weight limits. A properly installed bolt-on carrier can be secure, serviceable, and easy to replace without altering the trailer frame. It can also be repositioned if the original location interferes with a toolbox, jack, ramp, or new accessory.

Do not assume that every carrier described as “universal” will fit every trailer. Some inexpensive products are limited to 4-on-4-inch and 5-on-4-1/2-inch wheels, 10- or 12-inch utility-trailer tires, or frames no larger than 3 by 5 inches. The MaxxHaul 80071, for example, is a real bolt-on carrier with a published 100-pound maximum capacity, but it is intended for 10- and 12-inch utility-trailer wheels using 4-on-4-inch or 5-on-4-1/2-inch bolt patterns. It mounts to tongues up to 3 inches wide by 5 inches high and includes a locking bracket, with the padlock purchased separately. It is not a carrier for a 16-inch, 17.5-inch, or heavy commercial trailer wheel.

Weld-on carriers make sense when:

• You’re adding the carrier during a new trailer build, structural repair, or professionally engineered modification.
• The trailer’s frame geometry does not accept an appropriate bolt-on carrier.
• The complete spare is too heavy for readily available clamp-on hardware.
• You need a model-specific mount that clears a dump hoist, tilt deck, gooseneck structure, toolbox, winch, or loading system.
• The trailer manufacturer or qualified fabricator has approved the mounting location and welding procedure.

A weld-on installation is not automatically stronger or safer. Welding in the wrong location can damage a high-strength frame member, create a stress concentration, distort a rail, weaken a flange, damage wiring or hydraulic lines, and burn away the trailer’s corrosion protection. Never weld a carrier to an axle tube, suspension component, brake backing plate, coupler, safety-chain attachment, or engineered frame section without written manufacturer approval.

Diamond C trailers use the DM Difference Maker multi-stage coating system. Any welded retrofit will disturb the finish in the heat-affected area, so the bare metal and surrounding coating must be properly prepared and repaired after fabrication. Leaving a fresh weld, ground edge, or drilled hole unprotected invites corrosion beneath the carrier.

The Buyers Products 5201010 is an example of a verified universal bracket that can be bolted or welded. Buyers lists 14-gauge steel construction, a black powder-coated finish, and compatibility with tires mounted on rims up to 19.5 inches. It is primarily marketed for work trucks and commercial vehicles, so installation on a trailer still requires a structural mounting surface and confirmation that the complete tire-and-wheel assembly is suitable for the bracket and installation. Typical retail pricing is roughly $55 to $90.

With any bolt-on carrier, use the supplied or manufacturer-specified hardware. Do not automatically replace it with an unknown bolt from a garage drawer, and do not assume stainless hardware is stronger than the specified plated fastener. Match the required diameter, grade, thread, washers, locking nuts, and torque. Tighten the carrier according to its instructions, recheck it after the first loaded trip, and inspect it periodically for movement, cracked coating, elongated holes, bent brackets, rust, or loose wheel-retaining hardware.

Lockable Carriers: Worth It or Overkill?

Spare trailer wheels do get stolen. A visible 15- or 16-inch tire and wheel can be removed quickly if the carrier uses only a wing nut or ordinary lug nut. A lock will not stop a determined thief with power tools, but it can discourage a quick theft at a job site, hotel, trailhead, farm, storage lot, or unattended parking area.

There are several legitimate locking methods. Some U-bolt carriers use spin-on lock brackets and a small padlock. Other products use a plate that covers the wheel-retaining hardware. A locking lug nut can protect a stud-mounted spare, while a hardened cable can secure the wheel to the frame as a second layer. The lock should not be the only thing retaining the tire; the carrier’s primary hardware must hold the wheel securely even if the lock is removed.

The C.E. Smith 27202 is a practical low-cost option for compatible light-duty wheels. It fits 4- and 5-lug wheels from 8 through 15 inches, attaches to a suitable frame, tongue, or rail, and is sold with a lock. Because it is a compact U-bolt-style carrier, it should be used only where the frame dimensions, wheel fit, tire weight, and available thread engagement match the product’s published limitations.

The MaxxHaul 80071 uses a different approach: its locking bracket is arranged so the owner can add a padlock. The padlock is not included, and the carrier remains limited to its published 100-pound capacity and small 4-on-4-inch or 5-on-4-1/2-inch utility-trailer wheel applications. A lockable description does not make a light-duty carrier suitable for a heavier wheel.

Choose a weather-resistant lock that fits the carrier without leaving excessive exposed shackle. Closed-shackle or shrouded-shackle padlocks are harder to reach with cutters than long, exposed shackles. Position the lock so it does not rub the wheel, strike the trailer frame, collect standing water, or become inaccessible behind cargo.

Security hardware also needs maintenance. Road salt, mud, fertilizer, dust, and water can seize a lock long before the tire is needed. Lubricate it with a product approved by the lock manufacturer and open it periodically. Keep the key in the tow vehicle rather than in a toolbox attached to the trailer, and carry a backup key where it will still be available if the truck and trailer are separated.

Matching the Spare to Your Trailer

This part causes more problems than the carrier itself. The carrier is only a storage device. The spare must match the trailer’s hub, studs, brakes, wheel requirements, tire requirements, and actual operating load.

This table is a starting point, not a fitment chart. Trailer GVWR alone does not identify the wheel. A 7,000-pound GVWR tandem-axle utility trailer may use two 3,500-pound axles, 15-inch tires, and 5-lug hubs. The current Diamond C GTU is one example: it has a 7,000-pound GVWR, dual 3,500-pound Lippert brake axles, and 205/75R15 radial tires. By comparison, heavier Diamond C LPX and HDT configurations use 235/80R16 tires on many builds and offer 17.5-inch heavy-duty packages on applicable configurations.

Buy the spare from the trailer’s certification label, build sheet, owner’s documentation, existing wheel markings, and tire sidewall information. At minimum, verify all of the following:

• Tire size and construction, such as ST205/75R15 radial.
• Load range and maximum load capacity at the specified cold inflation pressure.
• Wheel diameter and width.
• Number of lug holes and exact bolt-circle diameter.
• Wheel stud diameter, thread, and required lug-nut style.
• Center-bore diameter and whether the wheel is lug-centric or hub-piloted.
• Wheel offset and backspacing.
• Wheel load rating and maximum pressure rating.
• Clearance around the brake drum, caliper, hub cap, grease cap, and suspension.

Lippert’s current axle guidance warns that wheel bolt circles can be close enough for an incorrect wheel to appear to fit. It also requires wheel capacity to match the tire and trailer ratings, identifies wheel offset as critical to axle capacity, and states that the replacement wheel must match the required rim contour. A wheel that slips over the studs is not necessarily the right wheel.

Do not describe a tire as adequate merely because it has the same load-range letter as another tire. Read the tire’s actual maximum load at its stated pressure, and confirm that the wheel can handle both that load and pressure. A higher load range may require more inflation pressure than the existing wheel or valve stem is rated to withstand. The trailer manufacturer’s cold inflation specification remains the controlling starting point.

For a tandem- or triple-axle trailer, tire diameter also matters. Installing a noticeably taller or shorter spare beside another tire on the same side can change how the load is shared between axles and tires. Match the original size and construction, and choose a spare with similar overall diameter and tread depth. The brand and tread pattern do not always have to be identical, but the tire must meet the trailer manufacturer’s specification and should not create a meaningful diameter mismatch.

A 205/75R15 tire has a calculated nominal diameter of about 27.1 inches. An ST235/80R16 is about 30.8 inches. Actual mounted dimensions can vary by tire model, rim width, inflation, and load, so measure the complete spare rather than relying only on the size formula.

Inspect the spare before every major trip. Check cold pressure, sidewall cracking, tread separation, cuts, bulges, valve-stem condition, wheel corrosion, and the tire’s date code. A spare can lose pressure or age out while appearing unused. Follow the tire and trailer manufacturers’ replacement guidance rather than assuming that visible tread means the tire is roadworthy.

A Few Things to Check Before You Buy

Before ordering a carrier, answer these three questions:

1. What structural member will support it? Measure the tongue or frame member’s width, height, wall shape, flange position, and available straight length. Identify whether it is square tube, rectangular tube, channel, I-beam, formed high-strength steel, aluminum, or a proprietary engineered section. Check both sides for wiring, hoses, fasteners, crossmembers, spring hangers, and other ob sides for wiring, hoses, fasteners, crossmembers, springstructions. A carrier listed for a 3-by-5-inch tongue will not automatically clamp correctly to a 5-inch channel or an I-beam flange.
2. What are the complete spare’s dimensions and weight? Measure the tire’s outside diameter, section width, wheel offset, center bore, and total mounted weight. Many carrier listings specify wheel diameter or bolt pattern but do not state a maximum outside tire diameter. A 15-inch wheel does not mean the assembly is 15 inches tall. As a reference, a 205/75R15 is roughly 27.1 inches in diameter, while an ST235/80R16 is roughly 30.8 inches. Heavy 16-inch and 17.5-inch assemblies can also weigh far more than a light-duty utility wheel.
3. What will move or need access around the carrier? Check the coupler, jack, safety chains, breakaway cable and switch, electrical plug, toolbox lids, hydraulic pump, tarp system, truck tailgate, bumper, dump body, tilt deck, ramps, doors, suspension travel, lights, license plate, tie-down points, and cargo path. Confirm that the spare can be removed while the trailer is loaded and parked on the shoulder. Also consider weight distribution: a forward-mounted spare adds tongue weight, while a heavy rear-mounted spare reduces tongue weight and can worsen trailer stability.

After choosing a location, temporarily position the actual spare there before drilling or welding. Cycle every door, ramp, jack, dump body, tilt deck, and toolbox. Connect the trailer to the tow vehicle and check full left and right turns. This simple mock-up can expose an interference problem that measurements alone miss.

Quick Comparison: Common Spare Tire Carriers

Those prices are carrier-only ballparks and can change with availability, shipping, and seller. They do not include the mounted spare, fabrication, coating repair, installation labor, or additional security hardware. More importantly, the products are not interchangeable. The MaxxHaul carrier is designed for small utility wheels, while the Fulton supports a broader range of 4-, 5-, and 6-lug wheels. The BAL and Lippert systems address specific under-cha16turn611575search0turn571249search0turn571249search2

What About Trailers That Come Ready for a Spare?

Some trailers include a carrier as standard equipment, while others offer a factory mount and matching spare as separate options. Factory placement is valuable because the manufacturer has already considered the frame structure, wheel package, ground clearance, wiring, suspension, deck operation, and intended loading arrangement.

Current Diamond C configurations illustrate why you should check the exact model instead of relying on a general brand assumption. The GTU Premium Tandem Axle Utility Trailer currently lists an under-frame spare mount in its configuration. LPX and HDT equipment trailers offer specific spare-mount choices, and current FMAX Fleetneck 2.0 gooseneck trailers use an under-deck winch location. The carrier and the matching spare may still be separate line i6view0turn533646view1turn533646view2turn891149search7

When shopping for a new trailer, ask whether the unit includes the carrier, the wheel and tire, or both. Also ask whether the spare matches the installed tire size, load range, wheel rating, stud size, and finish. A trailer can be “spare ready” without actually including a usable spare tire.

You can review equipment and utility trailers in current inventory and check the photographs, option list, and build information for the spare setup. Because specifications and options can differ by model, GVWR package, axle configuration, tire package, and production date, the VIN-specific build should always take priority over a generic listing.

If you’re buying used or adding a carrier to a trailer you already own, aftermarket options cover many light- and medium-duty situations. Heavier equipment, dump, tilt, deck-over, and gooseneck trailers may need a factory bracket or custom-fabricated mount. If the tongue geometry is unusual, the frame uses an engineered beam, the trailer has a V-nose body, or the spare is a heavy 16- or 17.5-inch assembly, our team at Spencer Trailers can help identify the trailer configuration and a suitable mounting approach before holes are drilled or welding begins.

What counts: do not leave on a long haul with a loose tire in the truck bed and assume it will fit the trailer. Carry a properly inflated, serviceable spare mounted on the correct wheel, secure it to a structurally appropriate carrier, and keep the jack, wheel chocks, lug wrench, torque wrench, reflective warning equipment, and any special sockets or keys where they can be reached. A carrier and matched spare are inexpensive compared with towing a loaded trailer, replacing a damaged hub, or waiting hours for a roadside tire service that may not carry your wheel pattern.

Wondering what else to add before your next big haul? Take a look at our current trailer inventory to see which trailers already have the frame, axle package, tire setup, storage, rams, and spare-tire provisions your work requires.