Can I Change The Trailer Plans? – Common Questions Answered

Can I change the trailer plans? We say: Build the trailer you want – start with our plans, then make it yours.

Yes, we sell trailer plans, a lot of them. But we also know a trailer build is personal. You have specific needs, ideas, and preferences. That is part of the fun – and part of the value in building it yourself.

Our plans include options to help you customize – that is in the design. However, sometimes you want to go further and change the trailer plans in ways not shown on the drawings. Sometimes you want to add your own ideas – and that is exactly what we expect.

That is where the questions start. We get a lot of emails asking great questions.

“Can I change this?”
“Can I modify that?”
“What happens if I do this or that differently?”
“Can I make big changes to the trailer plans?”

For a good overview, please see When It Is Safe To Customize The Plans. For specifics, see the Q&A below for several good questions (cleaned up a bit for clarity), along with our practical answers.

This guide answers many common questions about how customers want to change the trailer plans, including length, width, height, structure, and materials. If you are thinking about modifying the trailer plans, perhaps your question is in here too.

Can I Extend The Trailer?

Yes – within limits.

A change in trailer length of up to 12″ is generally acceptable. For larger changes, we recommend starting with plans for a longer trailer and shortening it to the length you need.

Example: The plans show a 16 ft deck, but you want 18 ft. In this case, start with 20 ft plans and shorten the frame to 18 ft. Shortening a trailer is always safer than making it longer.

As you change trailer length, adjust the axle position too. A good rule of thumb is:

Increase trailer length by 10″ → move the axle back 6″.
Decrease trailer length by 10″ → move the axle forward 6″.
Adjust axle position for loading – always more important than these guidelines.

A change in trailer length should also include redistributing cross members. Review the design, then update the number and spacing of cross members.

For more information, read the full article on How To Make A Trailer Longer. These guidelines apply to most utility and industrial trailers. However, tiny house trailers are different – see modifying a Tiny House Chassis trailer below before making length or width changes to one.

Can I Change The Trailer Width In The Plans?

Yes – this is a reasonable modification, but again, within limits. We also have a full article on this topic: How to make a trailer wider.

Narrowing a trailer for tight roads (like in Baja) is also doable. The method is similar to making a trailer wider:

Remove the width evenly from the center of the design.
Adjust cross member widths to match.
Modify the tongue diagonals (usually the angle of the diagonals) to maintain the frame overlap and connection geometry.
Update rear components like ramps or tail plates.

This type of modification is more difficult on an existing trailer, but see the article on changing trailer width for more information.

Can I Lift The Trailer Higher Than Shown In The Plans?

Yes – you can change the trailer plans to raise the trailer height. Here are several good ways to do it:

The easiest option is switching from drop axles to straight axles. It will raise the trailer 4 inches.
You can change to taller spring mounting brackets.
Another option is adding spacers between the spring mounting brackets and the trailer frame.
Larger diameter tires will raise the trailer and increase ground clearance.
Changing to an overslung suspension is another way to gain several inches.

Each of these increases trailer height in a different way. Taller spring brackets usually make a small change. Spacers can add a little lift or a lot, depending on implementation. Larger tires can make a big difference in both trailer ride height and rolling ease. Finally, a change to overslung axles will add several inches.

Some important things to watch if you change the trailer plans:

On tandem axles, tire spacing can become a limiting factor. Use of larger tires can cause the tires to touch.
Increasing equalizer length can help with spacing the axles, but then you also need taller mounts.
Increasing lift also raises the trailer center of gravity, which can reduce cornering stability.
All of these changes interact, so one modification may require other small changes too.

None of this is difficult, but none of it is in isolation either. Think through the full system before committing.

Can I Change C-Channel Frame Members To Tube – Or Tube To C-Channel?

Trailer frame front and rear channel members – Yes – you can substitute tube for channel. Make sure to:

Use a similar size and strength. Ex: substitute 4″ x 2″ x 3/16″ rectangular tube for 4″ x 5.4 lb C-channel.
Cap the tube ends.
Seal them properly to prevent internal rust.

Frame main beams – No – do not change these without verifying the engineering. The main beams are part of the structural design, so changes are not recommended unless you validate frame strength.

Tongue members – Maybe – Some parts can change, and often there is a note in the plans for diagonal supports in particular. If a material note is not there, please don’t change the tongue members.

Cross members are a mixed bag. Yes – you can change most materials if they have similar characteristics. As a rule of thumb:

Maintain at least the same height.
Use similar wall thickness.
Match or exceed the weight per foot.

If the replacement member meets these criteria, it is usually acceptable to change the trailer plans.

One caution for changes to tube – internal corrosion protection. Often cross members are pierced for deck bolts, which allow moisture in. Unless you live in a very dry environment, make sure the cross members will not collect internal moisture. This is one good reason cross members are most often L-angle or C-channel.

Can I Change A Straight Tongue To An A-Frame Tongue?

No – we do not recommend changing a straight tongue to an A-frame tongue. The tongue and connection to the frame are structural design. This is a high stress area of the trailer, so changes are not recommended.

On the other hand, you can certainly increase the diagonals, making the tongue more like an A-frame. A few important notes:

Standard A-frame tongues have frame members at 50 degrees, which limits the tongue length.
A longer tongue improves tracking and stability, which is why many of our smaller trailer designs use a straight tongue.
Some of our designs have an A-frame layout, but with a different angle to achieve the desired length. These designs also have the engineering to assure they work.

In general, we recommend following the tongue design shown in the plans. Many plans do show options for the tongue members and configuration. In those cases, you can follow instructions for an alternate design.

Can I Add A Beaver Tail Or Dovetail To The Trailer?

First, a clarification of “Beaver Tail” versus “Dovetail” because the terms are often used interchangeably.

If a “Beaver Tail” is movable (like a hydraulic tilt at the end of the trailer) then No – this adds significant structural complexity and requires engineering to change the trailer plans.
If a “Dovetail” is fixed as part of the frame structure, then Yes – in most cases you can change the trailer plans to include it.

For a dovetail, it involves:

Adjusting the rear frame geometry.
Modifying the cross member layout.
Revising the tail members or tail plate assembly.
Adjusting deck layout and support structure.
Changing how ramps are supported, or eliminating under-deck ramp storage.

It is not especially difficult, but it does require intentional design so load paths remain clean and strong. For more detail, see How to Join Beams, along with Connecting Structural Beams (like for a gooseneck or dovetail).

While the answer for a dovetail is yes, the addition significantly alters the trailer structure. It affects multiple parts of the frame and requires careful layout to maintain strength. Because of that, it is not recommended without significant skill and experience with fabrication.

Can I Change The Deck Material Or Layout?

Deck material is a great way to customize a trailer, and it usually does not require changing the trailer plans. It will make the trailer feel different, but structurally it serves the same purpose.

Most of our trailer plans include options for deck material. Common options include plywood (often the least expensive), wood planks (very common), or metal. Some of our car trailer plans even show split decks, where part of the deck is open.

Wood decks, especially double-layer plywood, are typically the heaviest and strongest.
Wood plank decks are very common and often preferred for appearance.
Metal decks are durable and low maintenance, but they can be noisy because the metal acts as an amplifier for every bump.
Metal sheet decks, especially aluminum, require closer support underneath. While this adds some complexity, metal is often the lightest option.

Deck material does not carry the primary frame loads, but it does distribute loads to the frame. It also affects stiffness, weight, usability, and durability. For more detail, see the article on Choosing Trailer Deck Material.

Can I Run Trailer Wiring Inside The Frame Tubes?

Yes – you can run wiring inside the frame tubes, but sometimes it will create other issues:

You may need extra holes for entry and exit points.
Some wiring, like brake circuits, requires splitting runs, which is more difficult inside a closed tube.
You must add grommets where the wires enter and exit to prevent vibration and fretting damage.
Moisture can collect inside the tubes if they are not fully sealed.

A better approach is to run the wiring in its own protected routing:

Run wiring in PVC conduit or wire loom.
Attach the conduit cleanly along the frame.
Keep the wires, conduit, and/or wire loom tucked up out of the way.
Secure it with proper clamps (Adel clamps work great).

This approach is fairly easy to install, more convenient to service later, allows frame beams to seal, and avoids long-term corrosion concerns. Best of all, this is not a change to the trailer plans – it is simply a better way to finish the build.

See our Wiring Diagram page for a lot more information about trailer wires.

Can I Change The Trailer Plans To Include An Enclosed Upper?

Yes – the trailer frame will certainly support an enclosed trailer, but this is a bigger topic than we can adequately address here. The structure above the deck is a separate design, including how it attaches to the main frame. If you are planning an enclosure, here are some things to investigate:

Determine how the walls will attach to the trailer frame.
If your enclosure is to be outside the frame (around the wheels), plan how the outriggers will connect.
Match your wall structure to your insulation thickness (if using insulation).
Size materials for the loads – snow, wind, cargo, and use conditions. It does not need to be heavy if the design is good.
Include triangulation in the wall structure to promote strength, prevent flex, and improve durability.
Plan how the exterior skin will attach, seal, and terminate at edges.
Design the roof for proper sealing, fastening, and water shedding.

The biggest challenge is not strength on day one – it is durability after miles of vibration, weather, and regular use.

Our trailer plans do not include enclosure design because there are too many possibilities for configuration.

The details and desires are highly personal.
There are so many variables – height, width, styles, doors, windows, materials, structure, load requirements, and more.
Each customer wants their own configuration – which we totally support.

That said, I am always happy to talk through concepts so you can change the trailer plans to meet your goals.

Can I Resize A Tiny House Trailer?

Yes – but resizing a tiny house trailer requires more care than similar changes in other trailers (see above).

Our tiny house trailers are different because the structure fully integrates to carry primary loads at the perimeter. Walls, roof loads, snow loads, and other forces all transfer to the edges of the frame. The integration and structural integrity of the trailer frame must be maintained even if changes are made to the width or length.

If axle position changes, the cross members and geometry near the axles must also move.
Geometry at the ends of the trailer to support the tongue and tail must remain.
Cross members between the ends and axles must be repositioned to match the new length.
Limits for size changes still apply, as discussed in the sections above.

With most utility trailers, small length or width changes are straightforward. With tiny house trailers, the frame is part of the building structure, not just the support underneath it. Changes to width and length are still doable – but there are more things to consider in the adjustments.

Final Thoughts – Should You Change The Trailer Plans?

In many cases, Yes – you can make changes, and often you should.

We design our plans to be flexible because real builds and customers are never identical. Small changes are often easy and completely reasonable. That said, keep this in mind:

Changes are rarely isolated. One modification often leads to others because components interact.
There are always limits. Understand the limits for changes you want to make. See this article about When Is It Safe To Customize The Plans for guidance.
Strength, clearance, and serviceability all matter.

If you approach it thoughtfully, you can change the trailer plans to fit your exact needs. Follow the guidance above to do it without compromising performance or safety.