How Many Wheels On A 18 Wheeler? Why Do Semi Trucks Have 18 Wheels?

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Semi-trucks generally come with a lot of wheels. But the number of wheels a semi-model will have depends on the load it travels per time.

Typically, a semi-truck usually has 18 wheels. However, not all semi-trucks have 18 wheels; some have 10, some have 26, and some have up to 34 wheels.

These 18 wheels on a regular semi-truck support the trailer carrying the load, stabilize the tractor head and guard the semi-truck against unexpected failure.

Do you need help knowing how many wheels a semi-truck comes with? This article is for you. It will provide extensive information on the number of wheels a semi-truck has.

In addition, it will also explain why there are numerous wheels on a semi-truck and why some semi-trucks have suspended wheels.

semis trucks 18 wheelers

What Number of Wheels Are Available on Semi Trucks?

A Semi-truck is a specific type of truck with a tractor head and a back trailer. The number of wheels on a semi-truck is usually 18. Still, this number is determined by the quantity of load the semi-truck carries at a time.

If additional trailers or more heavy loads are being transported, the semi trucks’ wheel count will be increased to balance the weight of the load.

A typical semi-truck tractor unit has 6 or 10 wheels, depending on the size of the back trailer. A heavy-duty tractor head unit has ten wheels, whereas a light-duty unit head has 6.

A typical semi-truck trailer, i.e., a tractor head with tow, has 6 to 12 wheels, depending on the size.

Note: Some semi-truck rims can accommodate two wheels (tires) at once, like 53-foot tractor semis, while others can only accommodate one.

Numerous Wheels on Large Trucks

What is The Number of Wheels on a Heavy-Duty Truck?

Heavy-duty semi-trucks are those semi-trucks whose wheel rims accommodate several tires. Semi-trucks under this category have between 10 to 16 wheels.

These semi trucks are mostly large trucks with hubs whose rims accommodate up to two tires on each side.

Such trucks are usually equipped with a tractor head with up to 10 wheels to help propel the trailer back efficiently. Based on how many axles a trailer on a semi-truck has, it can contain between 6 to 24 wheels.

Most substantial semi-trucks that carry up to 30,000 pounds of load have up to 16 or 18 wheels to balance the load.

Sometimes, the second set of double tyres may be added to the trailer’s back for extra large loads, bringing the total number of wheels to 20 to 24.

What is The Reason For The Numerous Wheels on Large Semi-Trucks?

One of the critical reasons why semi trucks use so many wheels is to distribute the load properly to all the wheels and guarantee the sustainability of the weight.

These numerous wheels keep the tires from being crushed or damaged prematurely under the force of heavy loads that weigh thousands of pounds.

Maintaining the semi-truck equilibrium while turning the steering and driving is another factor contributing to a semi-truck possessing numerous wheels.

If there are not enough wheels to support the semi truck’s weight and the load, the weight can force the car to slant or fall.

Do Semi-Trucks Have Spare Wheels?

A semi-truck having spare wheels is dependent on the type of truck. Most big 18-wheeler semi-trucks do not have the supplementary elevated wheels and light tires usually found on waste and garbage trucks.

While huge semi trucks have spare wheels since they carry a significant load simultaneously, others do not.

Many semi-trucks only sometimes move with excessive replacement parts because doing so would violate the trailer’s weight restriction.

Most semi-trucks – especially those who frequent a weigh station, do not usually have extra wheels.

Hence, they don’t surpass weight restrictions. A single extra tire can increase the semi truck’s weight and make transportation harder.

How Many Wheels Are Available on a Semi Truck’s Tractor Without Trailer?

Typical semi-truck tractors without trailers have a total of 6 wheels. However, in some cases, especially when the load is enormous, a semi truck’s tractor can have ten wheels – two tires on the front and eight at the back (double wheels on each axle hub).

The majority of semi-truck tractors are two-wheel, back-wheel drive vehicles. The two front tires push the tractor forward.

The wheels behind that are more numerous will pull any extra equipment, like a trailer coupled to the tractor.

containerize long rig

What Purpose Do The Suspended Wheels on Some Semi Trucks Serve?

Semi-trucks usually have weight limitations and regulations that the owners must follow to avoid overloading the semi-truck with goods above its weight limits.

But, in some semi trucks like garbage trucks, there are usually suspended wheels capable of carrying extra weight when necessary and as permitted by law.

However, the presence of these suspended wheels does not mean you should overburden the semi-truck.

As long as the load on the semi-truck has not surpassed its weight restriction, these wheels can be used for extra support when necessary.

Remember that the less load on your semi-truck, the easier it is for the truck’s axle to work.

The total strength of the axles should only be used when necessary because overstretching the axle can make propelling the semi-truck more challenging with time.

What Number of Wheels Are on Light-Duty Semi-Trucks?

Light-duty semi trucks are haulers, box trucks, and some transport trucks. Most light-duty, smaller semi trucks have only 14 wheels.

Most of these semi trucks have shorter back trailers for a sizable load quantity. They usually have six wheels in the tractor head that propel the car forward and another eight wheels for the trailer.

What Are The Number Of Steering Wheels On A Semi Truck?

A typical semi truck’s tractor head has three pairs of axles. The front axle has two steering wheels – one tyre/wheel on each hub.

Likewise, there are another two wheels on both sides of the back axles, referred to as the driving axles. The driving wheel, which is in the driver’s cabin, controls the steering wheels.

Are There Two Wheels on Both Sides of an Axle in a Semi Truck?

Most big semi trucks require two tires (wheels), partly because these wheels function with two to three axles to offset the burden of the load and gain force to keep the truck moving.

The double tire is usually necessary for semi trucks carrying up to 80,000 pounds of load to support the excess weight.

Usually, most semi-trucks have two wheels on each side of the axle to ensure that the semi-truck has balance while conveying goods from one location to another.

It’s not a must that the more minor variants of semi trucks that carry loads of smaller weight must have double wheels. Nonetheless, a semi-truck having two wheels on each side of the axle is better and safer.

FAQ about semi-wheels

These FAQs will offer more knowledge about semi-truck wheels.

Do 18-Wheelers Have Another Name?

The name ‘tractor trailer or 18-wheeler’ used to refer to most semi-trucks is the combo of a semi-truck’s tractor head and the back trailer. It is also referred to as a semi-tractor tractor trailer.

A semi-truck’s tractor and trailer collectively make up a tractor-trailer, usually known as an 18-wheeler, because of the total number of wheels on the car.

What Number of Wheels Are On a 6 x 2 Semi?

Generally, the 6 x 2 semi-trucks have a total of 6 wheels. The front axles have two steering wheels, and the rear driving axles have four wheels.

The 6×2 semi-trucks mean that two of the back axles get driven. One of the main benefits of this semi-truck model is that it does not use excess fuel. However, it also has a downside – it produces less power.

Is Driving An 18-Wheeler Truck Hard?

Technically, driving a typical semi-truck is easy. On the other hand, it’s not easy.

Most truck drivers reported that driving an 18-wheeler semi-truck isn’t tricky, but it has a learning curve.

You will need adequate driving skills and tenacity to control the truck effectively.

Final Thoughts

This article has answered your question about the number of wheels on a semi-truck, including why some semi-trucks have suspended wheels.

As stated earlier, a typical semi-truck has 18 tires (wheels). However, the number of wheels a semi-truck will have depends on the amount of load it carries.

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