The tie rod attaches the wheel's steering knuckle to the steering rack. Having an inner tie rod and outer tie rod gives the steering linkage two pivoting points for smoother wheel control.
An in-line ball joint makes up the inner tie rod. The inner tie rods are pivot points and are attached to the end of the center link. It is located closer to the center line of the vehicle and is accordingly named "inner tie rod." The inner tie rod is the first pivot point initiating the wheel to turn.
A right-angled ball joint makes up the outer tie rod. The steering knuckle is attached to the outer tie rod. The outer tie rod is what turns the wheel. It is the final pivot point initiating the wheel to turn. From the center of the vehicle, it is located farther out than the inner rod and is accordingly named "outer tie rod."
Problems arise in the tie rod when the ball joints become loose. Loosening is caused by wear. Steering wheels with a lot of play and/or poor control in steering may indicate a problem with the tie rods. Another sign of a worn tie rod is abnormal wear in the tires.
