Trailer types explained: dry van, reefer, flatbed, step deck, RGN and more

0:00Trailer types at a glance

Ask for a truck, and the first question back is: what trailer? Here are the nine common trailer types, what fits on each one, and how to pick.

It comes down to three questions. Does your freight need protection or temperature control? How tall and wide is it? And how heavy is it? Answer those, and the trailer picks itself. Freight Sidekick books all of them.

0:29The three road limits: weight, width, height

What are the legal size and weight limits for a truck in the US? There are three, and they decide which trailer you need.

The weight limit is 80,000 pounds gross, counting the truck, the trailer and the freight together. That's a federal limit. The width limit is 8 feet 6 inches, also federal. Height is set by each state: 13 feet 6 inches in most states, and many Western states allow 14 feet. Canadian provinces set their own limits.

Go past any limit, and the load is overweight or over-dimensional and may need a permit. Often the right low deck, or extra axles, keeps it legal. Keep that 13-foot-6 line in mind: every open-deck trailer in this video is a different answer to it.

1:16Dry van

A dry van is a fully enclosed trailer, and it's the default for general freight: anything that fits inside and doesn't need temperature control. Inside a 53-foot dry van, you get about 52 feet 6 inches of length, 8 feet 3 inches of width and 9 feet 2 inches of height.

The door opening is smaller, about 98 inches wide by 104 inches tall, so measure tall or wide pieces against the door. Roll-up doors take about 6 inches of width, and a little height, compared with swing doors.

A dry van carries 42,000 to 45,000 pounds of freight, fits 26 to 30 standard pallets, and holds about 3,400 to 3,800 cubic feet. It loads at a dock. Use one for boxed or palletized freight that needs to stay dry and secure.

2:09Refrigerated (reefer) trailer

A reefer, or refrigerated trailer, is a dry van with an insulated body and a cooling unit on the front, for anything that must stay cold, frozen, or inside a set temperature band.

It holds about -20 to 70 degrees Fahrenheit. The unit and insulation cost space: 2 to 5 feet of length in the nose, and a couple of inches all around. So the inside runs about 51 feet 7 inches long, 8 feet 1¼ inches wide, and about 8 feet 8 inches tall.

That's also why a reefer carries a little less than a dry van: about 43,000 pounds, in about 3,000 to 3,400 cubic feet. Use a reefer for food, pharmaceuticals, chemicals and other temperature-sensitive freight.

2:58Flatbed

A flatbed is an open deck with no walls and no roof, so freight loads from either side or from above, by crane or forklift. The deck is 48 to 53 feet long, 8 feet 6 inches wide, and about 5 feet off the ground.

That deck height matters. The height limit is 13 feet 6 inches in most states, and many Western states allow 14 feet. With 5 feet of deck, freight up to about 8 feet 6 inches tall stays legal.

A flatbed carries 46,000 to 48,000 pounds, more than a dry van, because the lighter open trailer leaves more of the 80,000 pounds for cargo. Freight is strapped or chained, and tarped when it needs weather protection. Use a flatbed for building materials, steel, lumber and machinery up to about 8½ feet tall.

3:52Step deck (drop deck)

A step deck, also called a drop deck, is a flatbed with a lower main deck and a short upper deck near the front. The lower deck is 37 to 42 feet long and sits 36 to 42 inches off the ground, about 18 inches lower than a flatbed.

The upper deck is 10 to 11 feet long, and both are 8 feet 6 inches wide. Dropping the deck buys height: freight up to about 10 feet tall stays legal, compared with about 8½ feet on a flatbed.

A step deck carries 44,000 to 47,000 pounds, and equipment can be forklifted on or driven up ramps. Use one when your freight is too tall for a flatbed, but under about 10 feet.

4:41Double drop

A double drop trailer has a deck that drops twice: down from a raised front deck into a low well in the middle, then back up over the rear axles.

The well is 24 to 30 feet long, 8 feet 6 inches wide, and only 18 to 24 inches off the ground. In that well, freight can be about 11½ to 12 feet tall, depending on how low the well sits.

A double drop carries about 40,000 pounds, up to 44,000. Freight goes into the well by crane or forklift, and very tall or wide loads may still need a permit. Use a double drop for freight about 10 to 12 feet tall.

5:27RGN (removable gooseneck)

An RGN, a type of lowboy, is a removable gooseneck trailer: a double drop whose front section, the gooseneck, comes off. With the gooseneck detached, the front of the deck lowers to the ground as a ramp, so heavy machinery can drive or roll straight on.

The well is 26 to 30 feet long, 8 feet 6 inches wide, and 18 to 24 inches off the ground, so freight up to about 12 feet tall fits, depending on how low the well sits.

An RGN carries 40,000 to 44,000 pounds. Added axles carry more, but those loads move under permit. Use an RGN for excavators, dozers and other equipment that drives on.

6:11Conestoga

A Conestoga is a flatbed or step deck with a rolling tarp on a frame: open-deck loading, with a van's weather protection. The tarp opens from either side, or retracts all the way for crane or forklift loading, so nobody tarps by hand.

A Conestoga is 48 to 53 feet long and 8 feet 6 inches wide, with 96 to 102 inches of usable height, or up to about 110 inches on a step-deck base.

The frame costs a little capacity compared with a bare flatbed: a Conestoga carries 42,000 to 44,000 pounds. Use one for freight that loads from the side or top and has to stay dry.

6:56Box truck

A box truck, or straight truck, has the cab and cargo box on one chassis, with no separate trailer. The box is 12 to 26 feet long, 8 feet wide, and 8 to 9 feet tall.

Watch the weight numbers: the big one is usually the truck's weight rating, 26,000 to 33,000 pounds, not what it carries. A box truck carries about 10,000 to 12,000 pounds of freight. A 26-foot truck that doesn't need a CDL is rated about 26,000 pounds, but carries about 10,000.

Box trucks turn tighter, fit tight streets, and often come with a liftgate where there's no dock. Use one for city deliveries and smaller loads.

7:40Power only

Power only means the carrier supplies the tractor and driver, and you supply the trailer. It's used for drop-and-hook, where a driver drops one trailer and hooks up another, and for moving your own trailers.

There's no trailer to choose, so capacity is whatever trailer you provide. Just make sure the tractor's hitch matches your trailer.

8:04Why lower decks carry taller freight

Why do lower trailer decks carry taller freight? Because the height limit counts the deck and the freight together. That limit is 13 feet 6 inches in most states, and many Western states allow 14 feet.

A flatbed's deck sits about 5 feet up, leaving about 8½ feet for freight. A step deck's lower deck sits 3 to 3½ feet up, leaving about 10 feet. Double drops and RGNs have wells 18 to 24 inches up, leaving about 11½ to 12 feet, depending on how low the well sits.

The deck drops, the freight gets taller, and the total stays legal. Any taller, and the load may need a permit.

8:50Which trailer fits my freight?

Which trailer fits your freight? Answer three questions. First, does it need protection or temperature control? If it has to stay cold or frozen, that's a reefer. If it just needs to stay dry and secure, a dry van.

Second, how tall and wide is it, and how does it load? If it's too tall or wide for a van, or loads by crane, it goes on an open deck, and height picks the deck: a flatbed up to about 8½ feet, a step deck up to about 10, a double drop up to about 12. If it drives on, an RGN. If it loads from the side but must stay dry, a Conestoga.

Third, how heavy is it? Each trailer has its own payload range, and for a smaller load or a city delivery, a box truck may be all you need.

Here's how that works in our trailer finder. 24 pallets of boxed goods, 38,000 pounds, no temperature need: dry van. A machine 9½ feet tall, 30,000 pounds: step deck, because it's too tall for a flatbed. An excavator, 11 feet tall: the finder suggests a double drop, and notes that an RGN works too for equipment that drives or rolls on. An excavator drives on, so an RGN is the better choice.

10:10How many pallets fit in a 53-foot trailer?

How many pallets fit in a 53-foot trailer? 26 standard 48 by 40 inch pallets, in a single layer. Turned to fit, up to about 30. And if the freight can be double-stacked, up to 52.

On dense loads, though, you'll usually run out of weight before you run out of space: a dry van carries 42,000 to 45,000 pounds of freight.

10:35Get a quote for the right trailer

Not sure which trailer you need? Tell us what you're shipping. Get a quote at freightsidekick.com/freight-quote, or call (877) 345-3838. Allison, our AI freight agent, answers around the clock.

Full specs for every trailer are in our trailer guide, at freightsidekick.com/resources/trailer-guide.