Trailer Configurations

As you begin the design process, one of the first things to consider is what type of configuration fits your needs best. Here are your main options:

  • Bumper Pull Trailers: Length options from 14' to 32'; Width of 7' to 8'5"; GVWR of 7,000 to 10,400 pounds
  • Gooseneck Trailers: Length options from 20' to 45'; Width of 7' to 8'5"; GVWR of 14,000 to 30,000 pounds
  • Semi Trailers (or Transporters): Length options from 40' to 53'; Width of 8'5"; GVWR of 68,000 pounds
  • Truck Body (or Van Body): Length options from 14' to 30'; Width of 7' to 8'5"; GVWR varies depending on truck chassis.

In addition to van bodies and truck bodies, Featherlite can also customize other unique vehicles including toterhomes and self-propelled type trucks.

Design Limits

Usually, as long you can imagine it and it's technically possible, it can be built. But there are a few regulatory parameters you should know about that concern the size and weight of the trailer.

Size

Critical dimensions for trailers that travel on public highways are regulated by each state. For the National Network (U.S. Interstate and U.S. Designated Highways), the states have adopted the federal size regulations and limitations shown below. On state highways, each state may have limitations that are more restrictive and less than the dimensions allowed by federal regulations. Federal regulations require states to allow reasonable access from the National Network to fuel and delivery. This is to make sure that the tractor and trailer fits on U.S. roads, can turn corners and will fit under bridges. The key items for this are:

  • Length: Overall length of the trailer may not be more than 53 feet. Certain equipment mounted on the front or rear of the trailer, such as air conditioners, generators and lifts, are excepted from this measurement. The distance from the king pin coupler to the center of rear axles cannot exceed 40 feet unless the trailer is used for motorsports where it can be 46 feet.
  • Width: Overall width of the trailer cannot exceed 102 inches (8.5 feet).
  • Height: Overall height cannot exceed 13.5 feet.

In the event that a particular state limits the size of the vehicle traveling through it, it is possible to obtain special permits for each trip. These are issued by the individual state and are generally easy to obtain. This will restrict your routes and increase cost, however.

Weight

Trailer axles may not carry more weight than the DOT limits or what they are rated for, whichever is less. Bumper pull and gooseneck trailers are typically available with one to three 6,000 to 10,000 pound capacity axles. Semi trailers or transporters have two 25,000 pound capacity rear axles.

DOT limits the rear axles of semi trailers to 20,000 pounds each if they are placed over 10 feet apart. If two axles are placed over 8 feet apart, they can carry up to 38,000 pounds combined. If they are placed 8 feet apart or closer, they can carry 34,000 pounds combined. The weight of the total rig (i.e., tractor, trailer and payload) cannot exceed 80,000 pounds.

For example, if you have a trailer that weighs 20,000 pounds empty and a tractor that weighs 20,000 pounds, you can add 40,000 pounds of payload to the trailer before you are at the 80,000 pound limit. If you add 20,000 pounds of interior build-out to the trailer, then you have a payload capacity of 20,000 pounds.

However, weight distribution can be a problem. Most often the overweight problems are with the trailer axles - the challenge being to move the weight forward to the driving axles. So when designing, try to keep heavy things towards the front of the trailer.

Next, see the customizations available on your specialty trailer.