Tie rod ends are the crucial meeting point between a vehicle's steering rack and steering knuckle. The rod end not only transmits the force from the steering rack to the wheels, but it also provides a pivot point for the steering to maintain its geometry. The rod end typically features a round end and has a threaded bolt perpendicular to it that is inserted into the knuckle. The rounded end also houses bearings that allow the bolt to pivot freely; this end is covered by a protective boot to keep dirt out. This design may look uncomplicated to the naked eye, but because it is so crucial to handling, the tolerances involved are very tight.