Everything There is to Know Before Buying Your Next Flatbed Trailer

If you’re in the market for a new or used flatbed trailer, this series How to Buy the Best Flatbed Trailer is for you. 

We’re going to look at how you can buy the best flatbed trailer spec’d with your particular requirements and needs in mind.

And we’ll review upgrades and options to consider for reducing your maintenance cost, reducing downtime, and maximizing efficiency and return on your investment.

Here are some of the topics we will be covering:

  • What are the different types of flatbed trailers?
  • Aluminum vs. steel flatbed, which is best?
  • What is the difference between a curtain side and Flatbed trailer?
  • What is a Conestoga kit?
  • How can I maximize my payload on a flatbed?
  • What is a bulkhead on a flatbed trailer?
  • How much weight can a 53’ flatbed trailer haul?
  • What is a coil package on a flatbed trailer?
  • Why are some semi-trailers bowed?
  • What is a beam rating on a flatbed trailer?
  • How can I increase my backhaul option on my flatbed semi?
  • How can I prevent screws from popping in my flatbed floor?
  • What is a Moffett Kit?
  • Load securement options for a flatbed trailer
  • Step deck vs. Lowboy, which is best?
  • What is a dunnage rack?




Choosing The Right Flatbed Trailer

[Read: “3 Types of Flatbed Semi-Trailers”]

A lot depends on what you want to get out of your trailer. Choosing the right flatbed trailer for you is going to depend on what you’re hauling, where you’re hauling, and how long you’re holding onto the trailer.

If you’re looking for something flashy, maybe an aluminum trailer is the way to go. But, if you want something to go to work, maybe you’re looking at a combo trailer. If you need something heavy-duty, an all-steel trailer could be right for you.

Aluminum Flatbeds




Aluminum flatbed trailers are typically your lightest option, lighter than steel or combination trailers, consisting entirely of aluminum – beam, side rails, and floors.

These trailers cost more than a combo and steel trailers, but on the upside, they do have a higher resale value.

Because aluminum deflects more than steel, these flatbeds are built with an arch (camber) in the trailer, which allows the beam to level as weight is added.

Combination Flatbeds


Photo of a combination flatbed depicting a steel beam.


Combo flatbed semi-trailers are comprised of a steel beam, aluminum floor, and aluminum side rails. They provide the weight-savings of aluminum with the strength of the steel beam.

Combo trailers are less expensive than aluminum trailers and slighter more expensive than steel.

Steel Flatbeds


Photo of an all steel flatbed.


Steel trailers are built entirely of steel, including the beam, side rail, and suspension hangers, making them heavier than aluminum or combo.

They are a lower upfront investment; however, you won’t get as much on the resale value. It’s built to last and will be a good work trailer.


  • Steel trailers have a wood floor that provides nearly unlimited options for dunnage securement.
  • Most durable out of the three. Since the entire trailer is steel fewer issues with corrosion due to dissimilar metals.
  • Cheapest upfront option


  • The wood floor will eventually wear out and will need to be replaced
  • Steel is more susceptible to rust, especially in the northeast.
  • Lesser resale value


What Are Curtain Side Trailers Used For?

[Read “Conestoga vs Curtainside Trailers”]

Photo of a curtain side trailer.


A curtainside trailer, or curtain van, is a dry van and a flatbed trailer combined into one trailer. It loads like a flatbed but protects like a van with a ceiling, front wall, and rear doors. The sides are open to allow access for loading, and the rear swing doors will enable it to be dock-loaded, similar to a dry van.

Curtains hang from the roof on each side of the trailer, slide open, and close to provide an enclosed trailer. On the Curtain side trailer, the frame does not move, and therefore top loading is not possible.


A photo of the inside of a curtainside trailer.


Curtain side trailers are an excellent option for loads that require more protection and special handling or when it’s more efficient to load from the side. It’s also a good option if you have multiple stops to make.

  • Curtain side trailers have a rear door like a dry van.
  • Typically has a support system for the roof, side and center supports, and a rear door frame.
  • Can be retrofitted to any flatbed but requires more modification to the flatbed trailer than a Conestoga kit.
  • It’s a heavier setup than the Conestoga kit because the system includes a roof, frame system, front bulkhead, and rear door.
  • It gives the option to side load or rear load the trailer.



5 Ways to Reduce the Weight of Your Flatbed Trailer


MAC trailer depicting cross member spacing.


[Read “7 Ways to Maximize Your Payload on a Flatbed Semi”]

The way to increase your payload is to take weight off of your flatbed trailer. Below are some ways to do that.

  1. Start with the right flatbed.
    Most importantly, you want to start with the right flatbed. Lightweight options include the all-aluminum MAC and the 4000AE, which at 8800 lbs. competes with all-aluminum flatbeds.
  2. Aluminum cross members.
    Going with aluminum vs. steel cross members saves approximately 400 lbs.
  3. Increase cross member spacing.
    Increasing the cross members spacing from 12″ to 18″ saves approximately 300-400 lbs.
  4. Wheels and tires.
    Low Pro 22.5” tires on aluminum wheels are approximately 500 lbs. lighter than 11R 24.5” on steel wheels.
  5. Closed tandem slider vs. spread axle.
    Spread axle weighs up to 500 lbs. less than a closed tandem sliding axle.


Why Are Some Semi Trailers Bowed?


Photo of an aluminum flatbed with arch in the beam, and no cross members.


[Read “Beam Ratings on a Flatbed Semi-Trailer”]

Aluminum trailers are lighter and less rigid than steel and flex a lot more than steel, so they’re built with an arch (Camber) to allow for flexing as the trailer flattens out when loaded heavily.

This arch might not be ideal for transporting long flat materials. Use dunnage racks to help fill that gap between the trailer’s arch and the product.

Increase Cross Member Spacing.

Space aluminum cross members closer together than steel cross members to support the additional weight from deflection, especially in applications where you’re rearing-loading with a forklift.

Combination and All-Steel Trailers.


Photo of combo flatbed semi trailer with cross braces.
* Photo of a combination trailer with steel beam


Combination and all steel trailers have less camber with the steel beam and, therefore, are flatter trailers.

Combination trailers typically include cross braces for additional support. The weight of the load is distributed through the cross braces and back to the steel beam itself.



How To Keep Screws from Popping and Waves in Your Flatbed Floor

Most flatbeds are not properly set up to back up to a dock with a forklift loading from the rear. Consider your cross member spacing and composition to help prevent those popping screws and waves in your floor.

Read [“5 Ways to Prevent Damage to Your Flatbed”]

Aluminum Crossmember Spacing

If you are rear loading or have concentrated loads, we recommend decreasing your cross members to a maximum spacing of 12″ because aluminum cross members have more deflection than steel.

Steel Crossmember Spacing

Steel cross members are stronger, so you can get away with spacing your cross members at 16″; however, you might still want to consider 12″ spacing.

Know What your Trailer is Capable of Hauling

It is important you need to understand how your trailer is spec’d and the load it’s equipped to handle.

A trailer with 24″ cross member spacing, and no side cross braces, should not be rear-loaded, and be mindful of the load toward the outside of the rail because the trailer is not set up to support the weight.


Load Securement Options for a Flatbed Semi-Trailer

Winches and Straps


A photo of winch and strap assembly.


Available in steel, galvanized steel, low profile for use with toolboxes and drop decks, winches are a very common way to secure a load on a flatbed.

They can be mounted on the driver side, curbside, or both sides of the trailer. It all depends on your philosophy. For the driver, it’s easier to work with straps on the driver’s side; however, it’s safer to adjust your load from the curbside if you’re pulled off the side of the road.

You might consider load securement points on both sides for taller loads to help prevent the load from shifting. Utility has a proprietary side rail with the winch tracks built into it, allowing winches to be placed on both sides of the trailer.

Spools and Pockets


A photo of pipe spools on side rail of trailer.


Depending on the manufacturer, you may or may not be able to use a pocket to secure a load.

Spools working load limits (WLL) will vary depending on the manufacturer. Be sure to check with them to understand the pipe spools rating.

For example, wrapping a chain around one spool can have one rating, but the rating may change if you wrap it around two spools. The angle at which the chain comes off the spool will also determine the load limit rating on the spool.

Consult with the manufacturer for chain ratings. Also, check with the DOT for load securement regulations, tie-down requirements for heavy equipment, chain ratings, etc.



J Hooks for Flatbed Semi.


J-Hooks (Flatbed J Plates) are an adjustable load securement system used with flat hook straps or chains.

The J Hook plates slide into the tracks located on both sides of the deck, and can be placed anywhere along the track.

  • J Plates provide many options for placement throughout the length of the trailer.
  • They are removable and can be stored on a standard bar rack or a toolbox.
  • J Hook ratings can vary based on manufacturer.

[Read: “Pop Up Chain Adapters, D Rings, and Container Locks.”]



Step Deck vs. Lowboy, Which is Best?


Photo of a step deck trailer.


Due to the lower rear deck height, step decks can be a great option for hauling equipment, tall loads, and other cargo.

Generally, any load under 10 ft. tall and 8 ft. wide can be loaded onto a step deck trailer. Small loaders, skid steers, small excavators, or bulldozers are examples of equipment you can potentially haul on a step deck.

We recommend going with a Removeable Gooseneck (RGN) or a Lowboy for larger or heavier equipment. A Lowboy can carry cargo up to 12 feet high and heavier loads.

Step decks are an excellent option for hauling midsized equipment and provide the versatility to haul other loads.

[Read more about: “Hauling Equipment on Step Decks and Flatbeds”]



What is The Best Bulkhead for My Flatbed Semi-Trailer?


a photo of bulkheads for semi-trailers.


What is a bulkhead on a flatbed?

Bulkheads are important to cargo control. They are affixed to the front end of a flatbed trailer to prevent forward movement of cargo and protect the driver carrying heavy loads.

What type of bulkhead is best for my flatbed?

There are two basic types of bulkheads for flatbed trailers, the wrap around and the flat.

Choosing the right bulkhead is important for both safety of the driver and the cargo. You want something durable enough to stand up to shifting cargo while not adding weight to your trailer.

Flat Bulkheads:

  • A flat bulkhead is sufficient if you won’t be loading cargo that requires additional reinforcement on the sides.
  • With the flat bulkhead, you’re not sacrificing any deck space, allowing pallets to be loaded up against the bulkhead.
  • Flat bulkheads are available in both corrugated and flat metal.

Wrap Around Bulkheads:

  • A wrap around bulkhead, or turnback bulkhead, has a return on either side which can provide extra support to help keep a load in place, and the turnback makes it easier to secure the load with side rail kits and panels.
  • Wrap arounds are available with returns of 10″ or up to 24″ in length.
  • Both bulkheads come DOT or Non-DOT rated.

[Read more about: “Bulkheads and Accessories”]


Flatbed Accessories


Many configurations are available depending on your needs, including bolt-on kits, steerable lift axles, and front and rear configurations.

Mount toolboxes between the spread axle or anywhere along the flatbed on either side.

Dunnage Racks


A photo of a Dunnage Rack.


What is a dunnage rack?

A dunnage rack provides storage on your semi-trailer flatbeds for the wood (or dunnage) while transporting unpalletized loads.

They’re mainly used on flatbed, drop-deck, and gooseneck trailers to free up space on your trailer bed to allow you to carry more cargo.

And, they come in many styles and configurations, including baskets styles with or without a floor, side mounts, cross trailer mounts, and can be designed to hold dunnage as needed.

[Read more about: “Lift Axles, Rear Axle Dumps, and Additional Accessories”]



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