Comprehensive Guide to Semi-trucks

Almost everyone sees a semi-truck every day but an average adult most likely doesn’t know too much about them. In this blog post, you’ll get answers to questions like what is a semi-truck? Why are they called semi-trucks?, and every other question you may have.

What are Semi-trucks?

According to Merriam-Webster, a semi-truck is made from the combination of a tractor unit and one or more semi-trailers to carry freight. You can also call a semi-truck a heavy-duty truck that is used to transport large loads. It’s also called a semi-tractor trailer. 

Why is it called a Semi-truck?

The original term for a semi-truck was a “trailer” but because trailers do not have a front set of wheels, this meant that they could not really be called that. Over time people began to call them semi-trailers, others just called them truck trailers or just trucks. 

Semi-trucks are also commonly called 18-wheelers, this term was coined from the 18 wheels that a semi has when hauling a trailer. Another common name you’ll hear is Tractor-trailer. All these names came from a place of combining a truck and a trailer, although most names are associated with trucks.

What Kinds of Semi-trucks are available?

There are different categories and brands of semi-trucks and that’s what we’ll be discussing in this section. 

There are two main categories of semis:

  • Day cabs
  • Sleepers

Although related they have different compartments and spaces.

Sleepers are used for long-haul trucking because they normally have  a bedroom compartment, that is made up of  a single bed and some storage space. Drivers can spend days living in their trucks and just get out to fill up their tanks or to take bathroom breaks.

There are different categories of sleepers, there are high-roof, mid-roof, or flat roof trucks each differently designed to give the driver room to stand up. High-roof trucks can be over 8 feet high, mid-roof trucks are mostly around 6 feet , and flat-roof trucks are about 5 feet or even less. 

The height of these roofs determines how comfortable the driver will be while driving or living in the truck, and this is why you need to be careful when choosing the brand of semi-trucks to buy. Although this height also contributes to places that the semi-truck can pass through, some tunnels and low bridges may not be able to accommodate high-roof semi-trucks.

Day cabs are slightly different because they have limited space for the driver and passengers. They are majorly used for short distances, most day cabs are used at ports and distribution centers because the driver has to go home at the end of his shift. Day cabs are often seen at places where things are shipped.

Trailers that semi-trucks drive can also be classified into:

  • Dry van and enclosed trailers
  • Flatbed trailers
  • Refrigerated trailers
  • Lowboy trailers

The most common of these categories are the dry van and enclosed trailers. They are used to carry and mainly protect cargo from severe weather conditions and road challenges. They are safer substitutes for flatbed trailers. Enclosed trailers are used for expensive cars and materials in need of protection.

Flatbed trailers are also very popular because they are versatile, they are mostly used to carry construction materials and they carry everything on a flat surface. The driver has to be extra careful to ensure that the materials are tied properly and firm. They carry materials that don’t  necessarily need protection.

Refrigerated trailers are related to dry van trailers although they are heavily insulated. There’s a built-in system in them to ensure that the goods are fresh and as the name implies they are used to transport frozen food and grocery.

Lowboy trailers transmit materials that surpass the legal height limit a truck can carry. They function like flatbeds but rest on the axles and are very close to the road. This gives the driver more freedom  while driving and helps to transport larger objects. 

How Much Does a Semi-truck Cost and Weigh?

The price of a semi-truck changes depending on the type of truck, the engine, and other features.

New semi-trucks prices generally start above $100,000, with more features they can get close to $200,000. Although buying used trucks can help beat down the prices, one has to be careful when buying used semi-trucks. Prices for used trucks are lower, around $40,000- $70,000, it can also go lower depending on condition, usage, features, make, and model. Prices can be as low as $10,000 for very old trucks.

As with the cost, the weight of a semi-truck varies a lot, different factors like the make and model of the truck as well as the engine can affect the weight.

Day cabs mostly weigh around 15-16,000 pounds, small sleepers (the flat roof ones) weigh about 1,000 pounds more and large sleepers can weigh over 18,000 pounds. Although the maximum weight for a semi-truck with a loaded trailer legally allowed in the United States is 80,000 pounds.

What’s the Height of a Semi-truck?

Most semi-trucks are between 6.5 and 14 feet, although the height depends on the kind of roof present in the truck. Most day cabs have tall roof caps, the roof cap is a curved piece coming over the roof of the truck making it more aerodynamic. The roof caps in day cabs allow air to flow smoothly up the front of the truck and across the top of the trailer attached behind.

According to a research report, semi-trucks in the United States are around 72 feet long, 8.5 feet wide, and 13.5 feet tall. This is however, brand dependent.

Examples of the Best Semi-trucks Brands

Many semi-trucks brands are notable and sell quality trucks, here are a few of them: 

  1. Freightliner

This brand was founded in 1942 and has been making one of the best semi-trucks on the market ever since then. It’s a top brand in North America and is said to sell more than 70,000 Class 8 trucks annually

Their class 8 truck line is called Cascadia and they have an electric truck also called eCascadia. But as great as Freightliners are, they have some downsides, one of which is getting repairs or maintenance for trucks which can prove to be a hassle with long waiting times. 

  1. Kenworth

Founded in 1923 by Harry Kent and Edgar Worthington and now is owned by a truck manufacturer that owns Peterbilt as well. They are the second largest semi-truck brand in the US and research shows they have 16% of the market share. Most Kenworth drivers prefer the Cummins engines which make the Kenworth trucks more luxurious than other brands although they have low operating and maintenance expenses.

  1. Peterbilt 

This brand started in the trucking industry in 1939 and it has a very similar market share with Kenworth, both owned by PACCAR. They have been reported to have sold approximately 2 800 class 8 trucks in 2020. Peterbilt has two non-electric class 8 truck high-quality models although they have significant differences. Model 379 has a classic look while Model 579 has a modern look with control that improves fuel efficiency. The model 579 also has the largest mattress of any truck in the trucking industry. 

  1. Volvo

Volvo started producing cars in 1927 in Sweden and then expanded into trucks and other construction equipment. Although they are very popular in Europe, they hold about 17.3% of the North American market.

Volvo recently began implementing dynamic steering into their vehicles which is one of the key reasons they are on this list. Some truckers prefer Volvos because they are smaller and lighter making them easy to drive, although their repairs tend to be very expensive compared to other truck brands.

  1. Mack

Mack is the oldest truck brands, producing trucks since 1900. Although Volvo purchased Mack in 2000, the brand is still relevant. 

Mack has produced three different models of Class 8 trucks: the Anthem, Pinnacle, and Granite. They have a unique customer service called GuardDog Connect. GuardDog Connect enables drivers to evade unforeseen downtime and spend more time on the road. Because Volvo controls Mack, it has a feature similar to Volvo’s dynamic steering and it’s called “command steer.”

Legal Restrictions for Semi-trucks 

You must pay attention to legal restrictions concerning the use of semi-trucks. According to federal law, a semi is not allowed to weigh more than 80,000 pounds in total when traveling on interstate highway roads. 

They are also not allowed to weigh more than 84,000 pounds on non-interstate highways, this means that a semi-trailer with cargo is not allowed to exceed 34,000 pounds and the remaining part of the pounds must be around 46,000-50,000 pounds.

Several states offer exceptions to this law for semis that are transporting specific goods. It’s also important to remember that semi-trucks should not be wider than 102 inches, higher than 16 feet for freeway roads, and longer than 48 feet. Although this number varies depending on the type of road, drivers must ensure at all times that the semi-trucks they are driving are within the guidelines.

A comprehensive guide to buying Semi-trucks

There are many details involved when buying a semi-truck. In this section, we’ll be talking about all it takes to buy a semi-truck and what to watch out for. 

What to Consider When Purchasing a Semi-truck

The first thing to consider when purchasing your semi-truck is the use of the truck. No doubt there are many reasons you might want to purchase a semi-truck, but you should think first of how the truck can serve you, thereby deciding on the truck that most suits the usage. 

You also need to decide if you want to buy new semi-trucks or a used one. With the information that you’ve read above you know the price ranges for purchasing a semi-truck, it should be considered if you ever want to buy one. 

Another thing to consider is the safety and warranty of the semi-truck. How safe is it on the road and what’s the report from other drivers, can the warranty cover a few months even after buying.

Buying a Used Semi-truck

This is a question a lot of people ask when they want to purchase a used semi-truck, here’s a list of a few things you should consider if you want to buy a truck that has been used by a former owner.

  1. Age and Mileage of the truck

You’ll need to first consider how long the truck was used for, this will be a great indicator of the health of the semi-truck. This doesn’t always mean that trucks with less usage time are in better condition. You can choose to go for an older truck that has been well maintained. 

  1. Previous owner and maintenance history 

You need to be concerned about who owned the truck before and even request a document that contains the maintenance issues, this will help you know if the truck has any maintenance issues. It’s also important that you purchase used semi-trucks from a reputable company, it’ll boost the chances of getting a good truck. 

  1. Consult with a pro

If you’re looking to buy used semi-trucks for the first time, it’s better to talk with someone who knows everything about semi-trucks. They’ll be able to guide and give advice on what to look out for during the purchase, they serve as a form of preventive measure for any mistake. 

Preventive Maintenance Measures for a Semi-truck

The Department of Labor has stressed that it’s not enough just to buy a semi-truck, you’ll need to learn how to maintain the truck and ensure it stays safe on the road. Here are a few tips on how to maintain certain parts of your semi-trucks

Fluids: You must consistently check your fluid levels during and after driving, leaving fluids can get problematic for the correct functioning of your truck. A driver must check the fuel gauge, oil level, antifreeze, and so on to be sure they are properly working. 

Tires: They are one of the most frequently used parts of any vehicle and are easily replaced and this is why every driver must check them often. Driving a semi-truck with a worn-out tire can cause a series of accidents and it poses a threat to everyone. Both air pressure and tread depth should be checked daily. 

Brakes: Brakes are extremely important in every vehicle and they also can get damaged very easily. This is why every driver must be conscious and do an extensive check before any trip. There must be no leaks in the air pressure system as this can cause brake failure. 

Electrical Parts: A lot of drivers tend to ignore the safety that lights bring to the vehicle. The lights are helping to communicate presence to every passerby and other drivers as well. Every truck should have functional warning lights and drivers should ensure the electrical wiring of the car is well connected. Poor connection can cause the truck to develop faults.

Windows and mirrors: Drivers also tend to ignore windows that are not working and broken side mirrors. The mirrors are important to see vehicles coming behind which can help prevent major and minor accidents. Windows are also important to stop hazards during and after driving, another important part to note is the windshield. Every part of the truck must be well maintained and protected at all times.

Engines of a Semi-truck

This is another important factor to consider when learning about semis. The engines in semi-trucks weigh about 2,880 pounds and they are built to run non-stop. This is why the engine of any semi-truck you’ll be buying must be built to be a great engine. 

As long as your semi-truck engine is dependable you can be sure you’re in good hands. It is also well known that diesel engines that produce more torque and power than gas engines. For efficiency, a 13- liter engine is said to generally achieve better performance than a 15 or 16-liter engine although it can be upgraded in the cause of usage. 

Having said that, some engines are more reliable and enduring than others, and here are some of the best engines for semi-trucks:

  1. PACCAR Engine

This is a  13-liter engine that can produce 500 horsepower and 1850 Nm of torque. Most trucks from Peterbilt and Kenworth use Paccar engines.

  1. Freightliner

The engines in the Freightliner trucks are 13, 15, and 16-liter engines and they can produce horsepower and torque ranging close to 2000 each.

  1. Mack/Volvo

The engines from this company have varying horsepower and torque from 600 to 2500.

  1. Navistar

This brand is a top producer for class 5-6 motors, although they have good engine quality, their class 8 engines may need more upkeep and periodic oil changes.

Insuring your Semi-truck

According to the U.S Truck Driver Anthropometric study report, there are over 3.5million truck drivers in the U.S currently which would mean more semi-trucks need to be insured, because of the federal law.

Federal law requires that large commercial trucking companies to carry insurance to compensate people who get injured in truck accidents. There are minimum insurance limits for large commercial trucks and vehicles, whether they transport hazardous material or carry passengers.

Insurance can financially cover an insured truck from any damage caused due to fire, accidents, theft, and even natural disasters. In 2020 more than 4000 lives were lost in accidents involving large trucks. Insurance for your semi-truck can’t be overemphasized.

DOT Checklist for a Semi-truck

A DOT inspection is a different test that checks if a commercial vehicle is in good working condition and this inspection is carried out by state troopers or enforcers under the instructions of the Federal Motor Carrier Safety Administration (FMCSA)

Here are the typical areas and internal systems that will need to be examined during a truck inspection:

  • Walk-around inspections will check the side mirrors, windows, steps, doors, lights, reflectors, and license plate
  • Checking tires and the tire pressure will include checking axle seals, tire inflation, and air pressure
  • Engine check includes inspecting the engine components like oil levels, fuel gauge function, and the cooling systems
  • The braking system checks will include the functionality of the brake pads, fluid, and hose
  • Vehicle interior inspections will check the seatbelts, horn, windshield, defroster, wipers, airbags, and so on
  • Lights and signals include checking the headlights, brake lights, beams, hazard, and turn signals
  • Coupling system check will include the electric lines, locking jaws, release arm, skid plate, pins, and bolts
  • The trailer part of the semi-trucks will also include checking frame, shock absorber, brake chamber and lining, slack adjuster, and push rod
  • Driver documentation is also important and will include CDL license, cargo manifest, daily logs, and medical examination card detail 

Basic Equipment needed in your Semi-truck

We’ve compiled a list of a few pieces of equipment that you need in your semi-truck

  • A well-stocked toolbox containing screwdrivers, pliers, wrenches, gloves, pony clamps, vice grips, and so on
  • Rackets and socket sets
  • Flashlights and road warning symbols and cones
  • Air pressure gauge and air pump
  • Cables and some extra fuses
  • Wheel chocks
  • Safety glasses
  • Wire cutter and electrical tape
  • Hammer and box knife 
  • Fire extinguisher 
  • First aid kit and some other cleaning supplies
  • Sleeper semi-truck would need bathroom supplies,some clothing and non-perishable food


At WHA Insurance we’re particular about sharing knowledge and offering help with insuring your semi-truck and any other vehicle. 

You can insure your semi-truck, with us at WHA Insurance. 

Also check out our other services here and let us know how we can serve you. 

Ian Berenger

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