[Sirrotica]

You can measure wear on the ball joint with a dial indicator. In PA as a state inspection mechanic (as I was) you were required to measure the ball joints and there is a table with allowed play that was a pass/fail for those components. Tie rods there was never any table because it would be next to impossible to set up a dial indictor to measure 2 types of play, lateral (up and down), and axial (side to side). The same is true for king pin type suspensions, there was a maximum amount of play allowed at the outer edge of the tire, 1/4 inch.

As independent suspension was refined the ball joint manufacturers had ball joint wear indicators that consisted of a raised area around the grease fitting. As the ball joint wears this raised area recedes and when it becomes flush with the area next to it, it is deemed in need of replacement.

Any time you could feel any play in a tie rod the car was failed for state inspection, there is no way to hold a toe in adjustment with loose tie rods. The easiest way to check is to raise on wheel off the ground and put your knees against the edge of the tire and see if you feel any play in the steering linkage. It may take two people at this stage to find out which tie rod is loose one to move the tire/wheel assembly, and one to watch where the play is coming from.