Selecting an Enclosed Cargo Trailer – Size

Width x Length x Height

When deciding the size of the trailer, people typically want to know sizes. The industry standard is measured on the outside rectangular portion of the trailer by Width then Length. For example a 6x12sa trailer is 6’ wide x 12’ long and in this example has a single axle (sa). If there is a V-nose on the trailer, that space is considered additional and can range from several inches to over a few feet depending on the model or extended tongue option. Trailer height is typically based off trailer size as a standard; however additional height can be added or subtracted. For example 5-wides are 5’ high, 6 & 7 wides are 6’ high & 8.5’ wides (car haulers) are 6’-6” high. Again this is the outside measurement, so it is a little shorter inside & has some obstructions like supports or cross member studs, dome lights & possibly ceiling liners.

Trailer openings /doors sizes

Trailers that have side doors typically come standard in 24”, 32” & 36” widths depending on trailer size. Car Haulers (8.5’ wide) typically have step wells due to the fact the trailer frame are 6”to 8” I-beams or channel making the trailer sit higher off the ground. Larger doors, front doors, side doors, escape doors, concession windows, front & side ramps are optional. The rear Barn Door(s) or Ramp typically has about a 6” to 7” frame on top & sides for the door(s) to close against. For example; a car hauler 8.5’ wide will have about 6” on each side making the opening closer to 7’-6” wide (keep in mind there is a guide wire for the ramp spring assist that is about an inch inside each side of the opening). Many car Haulers have a “no-show” 4’ Beaver Tail where the inside of the trailer slopes down a couple inches and meets the ramp. This allows for low profile, low clearance, vehicles to not bottom out while entering the trailer. This also adds a couple extra inches to the opening height of the trailer. For example; 8.5x16ta and larger trailers are typically 6’-6” high. With the 6” drop from the roof before the opening starts, this would leave about a 6’-0” opening for entering the back of the trailer; however because of the Beavertail there are a couple extra inches. (Note: a Beavertail is not desirable in concession style or some equipment trailers, because the floor slopes down for about the last 4’ in the back of the trailer making it difficult to level equipment).

Trailer Load Capability

The GVWR (gross vehicle weight rating) is the maximum the trailer can weigh fully loaded. There are many factors that can play into the load distribution reducing what can be put into the trailer, however a simple general rule is; if you have (2) 3500 Lbs axles the trailer GVWR is 7000 Lbs. If you subtract the weight of the trailers itself, you are left with the load capability. For example: a 7x16ta that has (2) 3500Lb axles weighs about 2150 Lbs and has a GVWR of 7000 Lbs., therefore you can put about 4850 Lbs (7000 Lbs – 2150 Lbs = 4850 Lbs) of cargo in it. If a larger load is required, you can always increase the size of the axles. If your cargo will have a small footprint and not distribute the load over a wide area, you may want to decrease the distance between center lines of the cross member supports under the floor. If there will be off-road or rough roads, you may want torsion axles over leaf springs for a smoother ride and better handling. (See Brakes below).

Tow Vehicle Capability

How much can your vehicle tow? See . You should always reference the owner’s manual or check with the manufacturer of your vehicle. Do Not base it off of what you see on the trailer hitch as these are made for a wide range of vehicles! There are many charts and references for this out there; however pulling a trailer too large can not only damage your vehicle, it is unsafe affecting handling and the ability to stop. Your vehicles Gross Combination Weight Rating (GCWR); which it the maximum weight of your vehicle & the loaded trailer, should also be listed in the Owner’s manual of your vehicle. You also have a Gross Axle Weight Rating (GAWR); which is the maximum weight limit for each specific axle on your vehicle at any given time specified by the manufacturer. This is a combination of the actual weight of the vehicle, the cargo & passengers plus the tongue weight of the trailer load. Keep in mind this is distributed over all the axles on your vehicle, so it may be a little difficult to determine. The Gross Axle Weight (GAW) is the amount a specific axle is carrying at any given time and changes as the vehicle moves or loads shift. As you can see we covered weights & not really other topics about your vehicles transmission, engine size, cooling system, Gear ratio of rear end or possible upgraded suspension.

Tongue load

This is the amount of weight that the trailer transfers to your hitch. The most widely accepted estimates range from 9 -15 percent of the loaded trailer weight with 10 percent being the common accepted number. For example; if you have a trailer that weighs 1800 lbs with 1000 lbs of cargo it is considered to be 2800 lbs. 10 percent of 2800 lbs is 280 lbs of tongue weight. Keep in mind that there are factors, like front or rear loading the trailer that affects this number. There are several methods that people use to measure this on the Internet.

Truck Bed length

The length of your truck bed is important if you are considering a gooseneck trailer. An 8’ bed length is recommended for ample clearance between the trailer & the cab of your truck. Often time’s people buy trailers without considering the fact that they have a short-bed, spare fuel tank or extended cab on their truck. Talk to your sales representative for specific questions.


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