A wiggle test is not accurate, don't bother with it. A wiggle test is with tires off the ground, gripping the tire and twisting it side to side. It looks impressive but does little to pin point wear.
A proper test is with the tires on the ground, preferably rough concrete so they grip, move the steering wheel enough to take the slop out each direction while watching each joint one at a time. No need to over steer it, just go till you feel resistance. One tire against a curb to really hold it also works.
I just finished up prep work for a Highway Patrol inspection of 170 school buses, I was the guy under them looking at the steering. The guy inside turning the wheel needs to know just how much effort is required to get a good test. We use wheel lifts to raise the buses enough just roll under them, this really holds the tires from turning which is important when checking. All straight axles, just like our trucks, only much bigger! Engines off, no power assist!
