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What Are Clearance Lights On A Semi Truck? (For Beginners)

Clearance lights are used to signal drivers of the existence of semi trucks on the road. It’s not for fashion or merely for illumination but rather for everyone’s safety.

Sure your state’s Department of Transportation has implemented relevant laws for clearance lights. 

Hence, the need to follow these regulations; otherwise, you’ll be charged with negligence.

Are you ready to venture into the world of clearance lights? Read on to find out more.

Here is a quick answer to What are Clearance Lights on a Semi Truck:

Clearance lights are amber and red lights found in the front and rear of a semi truck respectively. They notify pedestrians and other motorists on the road of the presence of a large vehicle. All trucks 80-inches and wider must mount clearance lights as mandated by U.S. federal vehicle regulations.

What Are Clearance Lights on a Semi Truck?

Clearance lights are the amber and red lights mandated by FMWSS-108 to be installed in your semi truck.

These lights alert any driver or pedestrians on the highway of the presence of a large vehicle. 

If you own a semi truck, whether you like it or not, you’re required to install clearance lights on your vehicle.

In the US, light companies certify their lighting products as compliant with the state’s DOT laws. Before buying one for your semi truck, check if the manufacturer certified the product.

Where are Clearance Lights on a Semi Truck?

Most trucks only have clearance lights on their roofs. 

Others have these lights in front and rear for both the left and right sides of a semi truck. 

The position of clearance lights depends on the laws in place for a particular country or state. Hence, check your state’s law to determine the proper location of these lights.

However, for US-based truckers, most state laws require that the clearance lights be installed in the front and rear of a vehicle. 

If your state doesn’t have any light regulations, you can refer to any US state laws. But if federal regulations and Department of Transportation laws exist, it shall take precedence over state law.

What Color should Clearance Lights be?

As provided in the Montana Code, the colors of clearances lights should be red and yellow (amber). 

For the left and right sides of the rear of a vehicle, the clearance lights have to be red. 

Take note that these lights have to be present and working on both sides. Thus, there shall be two minimum lights for the rear. 

Meanwhile, the clearance lights at the front of the truck shall be yellow or amber.

Both sides of the front should have two minimum lights. These lights also indicate the width and presence of the vehicle.

Do Clearance Lights have to be Amber?

The colors of the clearance lights depend on the placement of the light. 

As we’ve learned earlier, the designated color in front of the truck has to be amber, while the rear should be red. 

In case you’ve noticed the white lights in a semi truck, these are not clearance lights. These are license plate lamps used to illuminate the vehicle’s plate number. 

On the other hand, the amber lights you see at night are marker lights for illumination or during poor visibility.

Since the amber lights are placed front, you’ve probably concluded that all clearance lights should be in this color. However, it’s not. 

The red lights on the rear sides of a truck are another type of clearance light.

The colors of clearance lights should not be replaced by any other color.

When do you use Clearance Lights on a Semi Truck?

The purpose of clearance lights is to alert the driver that there’s a large vehicle nearby. This is for everyone’s safety on the road. 

If the truck is passing on a narrow or one-line road, you can use these lights to signal the other driver of your presence. In this way, the other driver can give way for you.

Under federal laws, a minimum of 80-inches width truck has to install clearance lights.

Is it Bad if you don’t have Clearance Lights on your Semi Truck?

It’s not bad if you don’t have clearance lights. After all, you don’t get to use them every day but in rare situations.

But if you drive the semi truck and the situation requires the use of clearance lights, this is where problems may occur.

If your semi-truck is under 80-inches in width, you can avail the exception of the 80-inches rule that needs clearance lights.

However, if your truck is at least 80-inches in width or beyond, you’ll be penalized for violating the regulations. A ticket may be issued, or you’ll face a penalty for negligence.

The worse thing is that you’ll also be charged with negligence plus damages if you encounter mishaps or road accidents.

What is the difference between marker lights and clearance lights?

One should not be confused between market and clearance lights. From colors to use and the benefits they provide, they’re different.

Here’s how they differ from one another:


Marker lights have to be in amber color. While you can use a clear case to cover the lights, the bulbs should be yellow. State laws strictly disallow the change of marker lights to any color.

Clearance lights are in red and amber color. As mentioned, the front clearance lights should use amber-colored bulbs, while the rear should be red bulbs.

All bulbs shall be covered by a clear case.


Like clearance lights, marker lights are in amber color and installed in the front and rear sides of the vehicle. Its function is to provide illumination during nighttime.

These lights are standard components of semi trucks, buses, and utility vehicles.

Meanwhile, clearance lights are “warning” lights. These are installed for safety precautions to prevent mishaps and road accidents.

You can use them any day or night when the necessity arises.


The driver of a semi truck will benefit the most in marker lights. This is because they’re used at night time when there’s poor visibility.

Whereas clearance lights are more beneficial for pedestrians and other vehicles on the road. They can prevent bumping into a large vehicle on the road, thereby preventing road accidents.


One of the main reasons it’s crucial to distinguish clearance and marker lights is the regulations imposed on them. 

Clearance lights are heavily regulated than marker lights. They are mandatory in commercial vehicles, while marker lights are not.

State laws are more lenient on marker lights. The rules make marker lights optional for semi-trucks, especially when using these lights will interfere with the efficiency of other vehicle safety equipment.

What are Clearance Lights on a Trailer?

Clearance lights are also mandatory for trailers with at least 80″ or broader dimensions.

These serve notice to other vehicles of the width of the trailer as viewed in front and back.

The lights must be placed at the same height unless the trailer has identification lights. If identification lights are also mounted, put the clearance lights below them.

What Color are Trailer Clearance Lights?

Like other trucks, trailers should have amber and red clearance lights. Again, amber bulbs are installed in front of the vehicle while read is for the rear.

However, US regulations allow dual-face lights for boat trailers, which means you can mount one amber and one red light either in front, rear, or both.

Typically, dual lights are placed on the trailer’s fender.

How many Clearance Lights do you need on a Trailer?

Trailers have seven various types of lights, namely clearance lights, reflectors, tail lights, stop lights, turn signals, brake lights, and license plate lights. 

Trailers need two amber and two red lights. All in all, trailers need four clearance lights.

According to US regulations, these lights shall be mounted to the trailer permanently. They are also required to be visible in the sense that no vehicle component is blocking them.

Fortunately, many manufactures produce lights with many functions.

You can now buy 1 product offering clearance, tail, turn signal lights, and the like. When buying trailer lights, you have to refer to the SAE codes to determine which role the light can perform.

The codes are the following:

S stands for stoplight

A stands for rear reflector

T stands for tail light

P2 stands for rear side marker lights

I stands for turn signal

How do you Install Trailer Clearance Lights?

The US laws have provided specific locations and proper installation for each trailer light. 

The clearance lights for the front and rear shall be at the same level. This means that no lights shall be higher or lower than the other.

The clearance lights for the rear shall maintain a 6 to 12″ distance. It can be lowered down when the header is less than 1″ long.

Meanwhile, the clearance light for the front must be as high as possible. It would be best if you were mindful of the trailer’s vertical centerline to estimate the distance of each light.

Do All Semi Trucks have Clearance Lights?

Legitimate semi truck manufacturers follow the Department of Transportation regulations. 

Hence, once you buy a semi truck, the clearance light is already mounted in your semi truck. The only time you’ll need to buy clearance separately is when these lights have worn.

To answer the question of semi trucks have clearance lights, the answer is yes.

It’s a general rule under US regulations that trucks having 80-inches in width must mount clearance lights on the vehicles. 

As such, if your semi truck does not meet the dimension criteria, your vehicle don’t need a clearance light.

Do Semi Trucks have to have Clearance Lights?

Perhaps you find clearance lights lavish or unfashionable. 

But whether you like it or not, these lights are mandatory. 

Whether you own a trailer, tractor, and truck for towing and hauling, you’re mandated to have clearance lights that are to be attached permanently at a particular location.

The only exception to the rule is when your truck is not at least 80″ wide. 

What are the Truck Clearance Lights Regulations?

As a general rule, clearance lights are regulated by the Federal Motor Vehicle Safety Standard (FMVSS). 

However, every trucker must refer to the federal or state regulations to know the placement of clearance lights. In case the state law is inconsistent with the higher laws, the latter shall prevail.

For instance, auxiliary or marker lights are mandatory in Texas, but the US Code allows removal of which for safety precautions. Thus, US Code takes precedence.

Truckers and manufacturers should follow the rules so they can adhere to the specifications required by law.

Truckers should ensure that each light is working correctly to avoid any violation and road accidents.

Respecting these laws shall not be motivated by compliance but for one’s safety.