Why Do Dump Trucks Have Extra Wheels?

Why Do Dump Trucks Have Extra Wheels
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Have you ever noticed how some dump trucks have strange extra wheels connected to them that seem to be there aimlessly?


Even when installed on the top of the truck, those aren’t backups and aren’t for adornment.

Then, why are they there? You must be wondering why do dump trucks have extra wheels. We’ll tell you all about it in this article.

Why do Dump Trucks have Extra Wheels?

The weight of a dump truck loaded with gravel can easily exceed the per-axle restriction. So, the additional wheels/axles are lowered to make the truck legal.

They are increased at other times to improve gas mileage and tire wear. This is the reason why do dump trucks have extra wheels.

Let’s talk in detail about it. The axle directly behind the dump truck is known as the pusher axle. On the other hand, the axle in the back is known as the tag axle.

Trucks have authorization only to carry a certain amount of weight on each axle by law. The dump truck can legally carry a larger weight with a dead axle.

Each state’s department for transport determines the maximum weight that a truck can carry per axle.

Because the weight of a dump truck loaded with gravel might easily exceed the per-axle restriction, the extra wheels/axles are reduced to make the truck eligible.

These laws differ from one state to the next, although there are certain commonalities.

A single axle, for example, cannot carry more than 20,000 pounds. Also, the tandem axle has a limit of roughly 34,000 pounds.

On the other hand, they are also increased to improve gas mileage and tire wear. The axle is lowered to enhance the weight capacity or to spread the cargo’s weight over more wheels.

This happens in times like crossing a bridge with a weight limit. When the axle is not in use, it is elevated off the ground to reduce tire and axle wear and boost grip on the other wheels.

In particularly tight bends, lifting one axle also eliminates lateral scouring of the additional axle. This allows the vehicle to rotate more easily.

A dead axle, also known as a lazy axle, is a free-rotating axle that is not part of the powertrain. You can consider the front-wheel-drive car’s rear axle as a dead axle.


That’s everything about why do dump trucks have extra wheels. It’s not easy to maneuver a dump truck.

Of course, it necessitates a great deal of expertise and experience. A dump truck’s extra wheels serve an important role in its safety.

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