A Tie Rod is the link that transmits steering motion from the rack or steering box to the steering arm on the upright, setting the toe angle of the steered wheel. Its length is adjustable and is what technicians change to set static toe. The position of its inner and outer pivots relative to the control arm pivots determines bump steer, the toe change that occurs as the suspension travels, because the tie rod must swing on an arc that matches the arc of the suspension link it works alongside. Tie rod ends must also allow the angular movement of both steering and suspension travel without binding, and any slack or deflection in them shows up directly as imprecise steering and unstable toe under load.