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The weight of a semi-truck has serious implications on the safe and legal hauling of goods. With most semi-trucks weighing over ten times more than a normal passenger vehicle, it’s easy to see why there are so many regulations about the weight of semi-trucks.
Exactly how much does a semi-truck weigh, though? Here, we won’t only go into how much a semi-truck weighs, but we will also break it down by section and explain why it all matters.
How much does a semi-truck weigh?
Semi-trucks are classified as class 8 vehicles by the Federal Highway Administration (FHA) since their gross vehicle weight rating (GVWR) is greater than 33,001 pounds. GVWR describes how much weight a tractor-trailer can theoretically carry safely.
To get the actual weight of an 18-wheeler you have to look at its gross vehicle weight (GVW). GVW is calculated by adding up the weight of the:
- Any accessories.
For example, a breakdown of a semi-truck with a GVW of 50,000 pounds could be:
- Weight of cab: 25,000 pounds.
- Weight of trailer: 10,000 pounds.
- Cargo weight: 15,000 pounds.
What is the maximum tractor-trailer weight?
The maximum weight of a tractor-trailer is 80,000 pounds, per FHA regulations.
This limit exists for safety reasons, as an overloaded trailer can:
- Damage the truck.
- Damage the road.
- Increase the risk of an accident.
These regulations are enforced by weigh stations, which are located sporadically on the nation’s highways. As the name implies, these stations check the weight of vehicles to make sure they do not surpass the federal weight limits. Any commercial vehicle over 10,000 pounds is required to stop at an open weigh station.
Three of the potential weight violations that can be caught at weigh stations are:
- A gross weight of over 80,000 pounds.
- A single-axle weight of over 20,000 pounds.
- A tandem-axle weight of over 34,000 pounds.
How much does the trailer of a semi-truck weigh?
The weight of a semi-truck's trailer is about 10,000 pounds when empty.
The weight of the empty trailer depends mainly on its length. Three common lengths of semi-truck trailers are:
- 48 feet long, weighing 9,000-10,000 pounds unloaded.
- 53 feet long, weighing 10,000-14,000 pounds unloaded.
- 28 feet long (known as a pup trailer), weighing around 4,500 pounds unloaded.
The weight of a loaded trailer, however, depends on the size of the load being hauled.
How much a trailer can carry is determined mainly by its number of axles. Most semi-truck trailers have either two or three axles. Tri-axle trailers are most often used when hauling loads that get the GVW close to the 80,000-pound limit.
A common example of how the weight could be distributed between tandems in a fully loaded, five-axle set-up is:
- The steer axle supporting 12,000 pounds
- The drive axles supporting 34,000 pounds.
- The tandem axles supporting 34,000 pounds.
How much does the cab of a semi-truck weigh?
The weight of a semi-truck's tractor is usually around 10,000-25,000 pounds.
The weight of the tractor depends on factors such as:
- What brand the engine is.
- If it’s a sleeper or day cab.
- How much it's designed to haul.
- How much fuel is in the tanks.
So, combining the weight of the cab with an empty trailer, an unloaded semi-truck weighs about 30,000-35,000 pounds.