How Many Wheels Does A Tractor-Trailer Have

Tractor-Trailers: How Many Wheels Does it Take to Move the World?

A tractor-trailer, also known as a semi-truck or an 18-wheeler, is the combination of a tractor unit at the front and a semi-trailer, one or more, at the back.

These vehicles are designed to help carry additional weight and cargo that wouldn’t normally fit on a regular truck.

Typically, tractor-trailers are very large and require a special driver’s license to operate. Since they’re so big, they also have more wheels than a standard truck.

But exactly how many wheels does a tractor-trailer have?

How Many Wheels Does A Tractor-Trailer Have?

In general, most tractor-trailers have four axles with four wheels on each axle. In addition, there’s one axle called the steering axle with two wheels – that’s the one that powers the tractor-trailer. So, there’s a total of 18 wheels on a standard tractor-trailer.

The number of wheels on a tractor-trailer depends on its size. It also depends on whether you count just the trailer itself or the tractor along with it; after all, they all have different numbers of wheels. For example, the front tractor may have six wheels, but the trailer at the back might be equipped with eight wheels. So, together, as a tractor-trailer, they have 14 wheels.

How many wheels can a tractor-trailer have?

Blue commercial 18 wheeler

Most semi-trucks, or tractor-trailers, are called 18-wheelers because they have 18 wheels. Some of these wheels are set up as dual wheels in order to distribute the weight of the truck and avoid problems.

With that said, some tractor-trailers may have fewer wheels than that, depending on their size and the cargo they’re carrying. For example, there are many 10-wheeler trucks that are used to transport lighter cargo.

On the other hand, there are also heavy-duty tractor-trailers that have more wheels. These wheels are often set up as dual wheels to avoid putting too much weight in one place and avoid making the truck too long.

So, the number of wheels strongly depends on the type of truck and its usage.

How many wheels does a compact tractor-trailer have?

Car trailer

The name ‘compact trailer’ is often used to describe a trailer that’s attached to the back of a car, personal truck, or SUV.

These are smaller, usually flat, and often used to transport smaller objects, such as furniture, mechanical equipment, or motorcycles.

Such compact trailers tend to have just two wheels at the back. They’re attached by the front to the back of the car, allowing for more space for cargo.

Sometimes you may come across larger trailers of the same kind that have around four wheels. These, however, are generally attached to larger cars and trucks since a standard, small car wouldn’t be able to handle the weight.

Does a semi-trailer have the same number of wheels as a semi-truck?

Semi truck vs Semi Trailer

The names ‘semi-truck’ and ‘semi-trailer’ are often used interchangeably to describe the same type of vehicle. But when it comes to technicalities, there’s a difference between the two.

A semi-truck can run on its own without any additional equipment or attachment. To put it simply, it’s the front of a large truck without any trailer at the back.

A semi-trailer, on the other hand, is hauled by a semi-truck, allowing for additional cargo to be transported at the back.

This type of trailer has wheels, often many, but no front axle or engine. So, it can run on its own unless it’s hauled by another vehicle.

Because of that, a semi-trailer and semi-truck have different numbers of wheels.

A semi-truck usually has two to four wheels that power the vehicle and haul the trailer. The semi-trailer at the back is typically equipped with anywhere from six to ten wheels.

How many spare tires does a tractor-trailer have?

Semi truck

Just like with any other vehicle, accidents happen, and a tractor-trailer may sometimes need a change of tires. So, you may wonder how many, if any, spare tires tractor-trailers carry.

As with any vehicle, the answer depends on the model and type of truck. Some carry one or two spare tires, but others don’t carry any at all.

The equipment to change a tire on a semi-truck is very heavy. In addition, it’s quite a difficult task to perform.

Because of that, most trucking companies have a contract with tire repair companies that come and change the tires on the go.

This reduces the time spent on fixing the tire as well as helps ensure that the job is done properly.

Are all wheels on a tractor-trailer the same size?

Semi truck tires

In general, the wheels on the tractor and trailer have to match, so they need to be the same size. This is because different wheel sizes can make the tractor-trailer unstable, negatively affecting safety.

That being said, there are many wheel sizes for tractor-trailers, both for the front tractor and the trailer itself. So, there are many options to choose from.

Tractor-trailer wheels and tires are much different from those of regular trucks and cars. That’s because they need to be able to carry lots of weight while maintaining power.

So, they’re more durable than regular wheels and tires.

If you’re wondering which wheel size is the best for a tractor-trailer, then you need to think about what the vehicle will be used for.

For instance, larger wheels are often more suited for harder jobs that require the transportation of heavier cargo. But slightly smaller wheels might be better for shorter journeys.

So, it’s always important to keep these factors in mind when changing tires.


The number of wheels on a tractor-trailer depends on several factors, such as the type of tractor-trailer, its size, and the type of cargo it transports.

As a result, tractor-trailers may have anywhere from 12 to 18 wheels.

In addition, it’s possible to attach various trailers to a tractor. This means that the number of wheels can change based on the trailer attached to the actual tractor engine.

Sources: Research Gate, Springer, and Science Direct

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