The tie rod end is part of the vehicle’s steering mechanism. Depending on the type of system, there can be an inner and outer tie rod for the mechanical box system, or outer tie rod ends only, in the more popular rack and pinion system. In the rack and pinion system, the tie rod end is the connection between the axial joint and the wheels, transmitting force from the rack gear to the steering knuckle. It is one of the major pivots in the steering system, causing the wheels to turn.