How Long Is an 18 Wheeler?

Author: HALIM
Updated On:

An 18-wheeler, also known as a semi-truck and trailer combination,  is a freight vehicle with eighteen wheels. Most industries use 18-wheelers to transport heavy cargo, machinery, unsafe materials, and batches of retail goods.

The vehicle carries cargo evenly and spreads the weight across a larger surface area than most trucks. A truck’s cab style can influence the length, but most 18-wheelers measure between seventy and eighty feet long. This article will explore why the 18-wheeler is an impressive vehicle, according to pro truck drivers. 

What Is an 18 Wheeler?

The truck is a combination of two parts: a trailer with no engine and a tractor unit carrying an engine. It has five axles, three under the truck unit and two in the trailer section.

However, the number of axles may vary depending on the truck’s design and what it carries. The semi-truck has two steering wheels in the front and eight wheels attached to the ends of two axles.

Eight wheels are attached to two axles at the trailer’s rear end, exactly like the middle portion.  The 18-wheeler’s wheel arrangement makes it suitable for carrying heavy-duty materials and potentially harmful chemicals. An 18-wheeler trailer can carry up to 80000 pounds; this is where most of the weight is spread out.

Most trailers have movable tandem axles at the rear, which can aid in the weight distribution of the cargo. The usage of 18-wheelers dates back as early as 1984. Winton Motor Carriage Company of Cleveland CEO Alexander Winton invented the idea behind the vehicle. Looking to hire or rent a big rig wheeler? Here is how much to rent an 18 wheeler truck!


How Long Is an 18 Wheeler?

Lengths of most 18-wheeler trucks vary between seventy and eighty feet; most have a standard height of thirteen feet. The length of the tractor and the cab’s design influence the semi-truck’s dimensions.

Most measurements are taken from the front of the cab’s bumper to the trailer’s rear. Semi-trailers can measure between 48 and 53 feet; thus, they make up most of the tractor-trailer combination

A bobtail truck, a tractor unit without the trailer attached, is usually twenty-four feet long. The addition of a semi-trailer pushes the length up, which makes the total measurement much greater.

Some instances may call for two trailers, for example, transporting goods that shouldn’t be in contact with one another. Though double trailers may be more efficient, they impact the total length of the 18-wheeler. 

Since the legal length limit for 18-wheelers is 80 the double trailer combination cannot exceed sixty-five feet. So, each trailer has to be twenty-nine feet or less in length, and they cannot exceed thirty-six thousand pounds each. TIPS: What is the longest gooseneck trailer allowed on road in below USA states?

Triple trailers are legal in thirteen U.S states, including Colorado, Indiana, Oklahoma, Nevada, Nebraska, Arizona, Utah, Oregon, Kansas, Montana, Ohio, and North plus South Dakota.

As the name states, this 18-wheeler has three trailers instead of the single or double you’re familiar with. TIPS: Can you drive a semi bobtail without a CDL and why?


The Various Types of Semi-trailers

Your trailer’s type, length, and height play a crucial role in your transporting business. These factors determine how much cargo you can carry, what goods you can carry, and the ideal trip duration. Below is a round-up list of the most popular trailer types and cargo they’re most suited to transport. 

  • Lowboy: This trailer sits closer to the ground than other trailer types due to the double-level drop on its deck. The dip in deck height is between the first set of rear wheels and the truck’s U-shaped gooseneck. A unique advantage of this trailer is its ability to carry tall cargo, large plus heavy machinery, and building materials. 
  • Flatbed: The flatbed trailer is one of the most common types; it is simply a flat deck surface. Its open layout is ideal for carrying large but light-weight items, like construction materials. The maximum weight that most flatbeds can carry is forty-eight thousand pounds. This is a huge difference from the standard eighty-thousand-pound weight most 18-wheeler trailers can carry. Since it has no enclosure, this trailer can’t protect the cargo from harsh weather and road conditions. 
  • Reefer: This trailer is one you’re most used to seeing on the road; it’s usually decorated with colorful pictures of foodstuffs. Reefers are rectangular-shaped containers with temperature control systems that transport temperature-sensitive and perishable foods. The constant temperature in reefer container ensures that your cargo arrives in mint condition. 
  • Dumper: This trailer has a hydraulics system that allows you to load and offload cargo easily. It’s ideal for transporting plus depositing loose or rocky materials like debris, coal, gravel, and dirt at a specific location. The hydraulic system sets the dumper trailer apart from the tipper trailer. But, both trailers can carry loose materials because they have similar builds and sizes. 
  • Drop-deck: This trailer type is similar to the Lowboy, except it has one perpendicular dip rather than two. The deck is flat, just like the Flatbed trailer, and it can also carry similar cargo. You can use a drop-deck trailer for cargo too tall or too wide to fit onto standard flatbed trailers. The maximum legal weight for drop decks is forty-eight thousand pounds. A dip in the deck prevents the weight from wobbling and makes towing easier. 
  • Dry Van: A dry van trailer is an enclosed container that carries non-temperature-sensitive cargo. The insides of the container are lined with foam, and they’re ideal for transporting general cargo like clothing, electronics, furniture, and machinery. Dry van trailers don’t usually carry heavy goods, but they carry large quantities well. One of the dry van’s main advantages is that it protects your goods from harsh weather climates. 

Frequently Asked Questions (FAQs)

1. Why is it called a semi-truck or trailer? 

‘Semi’ indicates that neither the truck nor trailer is a sole running unit, only half. You can drive a semi-truck without an attached trailer, but it’s non-operational as you can’t transport cargo. Semi-trailers can’t function when they’re not attached to a semi-truck. 

2. What is a fifth-wheel coupling? 

A fifth wheel coupling is a device that links the semi-trailer to the semi-tractor unit. This device is also known as a hitch and is shaped like a horseshoe. You must inspect the fifth-wheel coupling every ten thousand kilometers or monthly. 

3. Is driving an 18-wheeler hard? 

Driving an 18-wheeler carrying thousands of pounds of cargo is harder than driving your standard vehicle. Due to this, 18-wheeler drivers require a CDL license to operate the vehicle. This license ensures that you can drive vehicles weighing over 26,001 pounds and covers Class A, B, and C vehicles. 

4. How long can an 18-wheeler travel on a full tank? 

The duration depends on how well you maintain your vehicle and how old it is. 18-wheelers can travel for 2100 miles when brand new; over time and with use, the distance gradually decreases. 

5. What is the longest legal trailer length? 

Trailers usually measure between forty and fifty-three feet, but the legal length limit is sixty-five feet. 


The various types of semi-trailers leave plenty of room for you to choose your type of 18-wheeler. Semi-trailers influence the driver’s overall experience; they ensure that the freight weight is evenly spread across the vehicle.

Thus, you must select the most suitable type for your needs. 18-wheelers are large and durable, making them reliable means of carrying large cargo over long distances. They usually have a life expectancy of fifteen years when driven carefully and maintained properly. 

Finding the right 18-wheeler involves thorough research, usually centered around the cargo you want to transport. By now, you should have an understanding of the components that influence the length of the vehicle.

The length of an 18-wheeler varies, depending on its design, semi-trailer type, and cab style. However, most 18-wheelers range between seventy and eighty feet long, and the trailer cannot exceed fifty-nine feet. This vehicle is the most effective method of transporting various heavy-duty items from one place to another. 


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