Thanks everyone for the advice. My first step coming home today from work was to check the lower ball joints.
I have a dial gauge & clamp mechanism (for testing rotor runout); but I can't imagine how I'm supposed to apply 66 foot pounds of force to the lug nuts as described in the Toyota FSM.
How would anyone perform the test in the FSM?
Moving forward, I floor jacked the 4runner up by the center jack point below the engine & performed the recommended simple tire-shake test with the tires up in the air.
(Note: I tried to put the 4runner on jack stands, but failed as per this thread.)
After jacking the centerpoint so that the wheels were freely dangling in the air, I shook the wheel with my hands at 12 & 6 o'clock; there was no perceptible motion of the lower ball joints.
However, when shaking with my hands at 3 & 9 o'clock. there was an audible click which was hard to pinpoint where it was coming from. It seemed to be coming from inside the steering mechanism boot on the driver's side (
see more detail below) but the tire that wore badly was the passenger side.
I then ran the LBJ pry-bar test from this URL - and (on both sides) my 4Runner lower ball joints didn't budge a bit:
- VERY BAD Ball Joints - WATCH THIS!!! - YouTube
Did I do that test right?
Here is the pry bar test on the passenger side (bad) tire:
Here is that same test on the driver side (good) tire:
Both sides seemed pretty tight to me.
The only thing that seemed awry was that slight clicking sound when shaking the wheel at the 3 o'clock and 9 o'clock position.When I shook either one of the wheels, I could see the other wheel moving also.
Based on this Ford Explorer video, it seems (I think) my driver side
inner tie rod end (inside the boot) is where (I think) the slight clicking is occurring when I shake at the 3 and 9 o'clock position.
Front Suspension & Steering Inspection - YouTube
The weird thing is that the driver side is not the tire that is wearing abnormally!
I'm not sure if anything is actually wrong with the ball joints and/or tie rod ends yet.
Any advice?