A tag axle is typically found on a semi tractor. It is the axle behind the drive axle and is generally able to be elevated from contacting 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 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.
