We are independent & ad-supported. We may earn a commission for purchases made through our links.

Advertiser Disclosure

Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.

How We Make Money

We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently from our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is a Tag Axle?

By Lori Kilchermann
Updated May 23, 2024
Our promise to you
WikiMotors is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At WikiMotors, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

A tag axle is typically found on a semi tractor. It is the axle behind the drive axle and is usually able to be elevated from making contact with the roadway when not needed. It can also be found on semi trailers. These are also able to be lifted when not in use. This allows the tires to avoid unnecessary wear and also saves fuel. The axle is lowered when it becomes necessary to help spread the vehicle's weight over a greater area. It is also possible to find a tag axle on farm equipment, as well as certain heavy construction machinery.

Most tag axle systems are air operated. The driver or operator is able to control the axle by moving a switch inside the driver's compartment of the vehicle. By adding air to the axle, the driver can take weight off of the other axles on the vehicle. Conversely, removing air will place the weight on the other axles as the tag axle rises off of the road's surface. This helps enable drivers to obey certain seasonal vehicle weight restrictions or on certain weight-limited roads.

In foul weather, the operator may choose to lift the tag axle in an attempt to place more weight on the drive axle. This will create better traction and help the driver control the vehicle. The driver may also choose to lift a tag axle when maneuvering into a tight spot. This will allow the vehicle to turn easier rather than dragging and sliding an extra axle around on a parking lot. This also saves on tire wear.

When being weighed on a scale, the operator may be advised to reposition his or her axle to meet weight restrictions. Many roads have restrictions that require a vehicle to have a certain amount of weight distributed between all of its axles. By adjusting the pressure that the tag axle pushes against the road, the driver can vary the weight that each axle displaces upon the road's surface. This allows the vehicle to meet the required restriction and legally travel upon the road.

Certain vehicles have many such axles. Vehicles used to move over-size loads may have many air adjustable axles. This allows the trucks to distribute the weight of the over-limit cargo evenly over a greater distance and greater number of axles. It also allows the vehicle to turn much easier when it is not carrying a load. The driver can choose to use only the number of axles that are needed and avoid consuming excess fuel when the vehicle is empty.

WikiMotors is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.

Discussion Comments

By Sporkasia — On Feb 01, 2014

Drentel - I have heard some of the negative talk these coaches, but I saw a tag axle for sale and test drove it. It handles well and one thing I really liked is that the rear end is less likely to bottom out or drag when driving up and down ramps or over depressions.

By Drentel — On Feb 01, 2014

Tag axles are available on coaches and there is some debate as to whether they are better than the single rear axle. One advantage is that they allow you to carry more weight, but I have heard some drivers complain that buses with tag axles are more difficult to handle, so that might mean these vehicles are more dangerous than the single rear axles.

By Animandel — On Jan 31, 2014

I find it fascinating that big trucks and other vehicles have an axle that can be engaged and disengaged so easily with air pressure. I was unaware of this feature on tractors and trailers. From reading the article, I think the use of these tag axles makes the big rigs safer, which means the roads are safer for everybody; and it's hard to find a reason to argue with that.

WikiMotors, in your inbox

Our latest articles, guides, and more, delivered daily.

WikiMotors, in your inbox

Our latest articles, guides, and more, delivered daily.