A tube fender is constructed from a piece of pipe that is bent and positioned to cover the outer edge of a vehicle's tire. Typically found on off-road vehicles, particularly rock crawling-type vehicles, the tube fender prevents the vehicle from becoming hung up on an obstacle such as a rock or tree stump as it passes over it. Another feature of the tube fender that makes it popular with the rock crawling community is its ability to slide over the surface of a rock. By sliding over the rock's surface, the tube fender allows the vehicle to slide easily along the course of the trail without the likelihood of becoming stuck on an obstacle due to exterior body tin.
In some applications, the tube fender is simply fitted around the body work of the vehicle. This type of exoskeleton-type design functions more as a body preserver, preventing the body panels of the vehicle from coming into contact with obstacles and rocks along a trail. These versions typically link the tube fender with the running board tubes to create a complete protection package. The type of pipe used in this application is usually mild steel tubing. This pipe is more easily crushed than chrome molly, however, it is much less costly and is easier to be welded and repaired out on the trail.
For all out purpose-built rock crawling buggies, the tube fender commonly replaces any type of body panel. Using the fender only for the intended purpose of creating a component in which the rest of the vehicle might slide over an obstacle, the pipe is often the more expensive chrome molly tubing. This type of pipe is much stronger as well as lighter. The downside to using this pipe is the expense as well as the requirement of Tungsten Inert Gas (TIG) weld when making repairs. A trail-side TIG welder is much more costly than a simple arc welder or Metal Inert Gas (MIG) welding rig.
Some other variations of the tube fender can be found on ice racing motorcycles. In this configuration, the tube fender is used to protect other riders and motorcycles from becoming damaged by the ice picks used on the racer's tires. Typically fashioned in a continual loop, this type of fender design runs nearly all of the way around the tires, coming dangerously close to the ice as it encircles the studded rubber.