Returning from a 3000 mile trip I recently made, I've noticed that the
outside 1/5 of the left front tire on my '87 Syncro has worn nearly bald.
Before I make any tire changes, I need to figure out what's causing this.
Is it an alignment problem, a failed CV joint, or the dreaded Viscous
Coupling (please no!)?

What I've noticed:

1. The vehicle does not seem to pull or shimmy to any noticeable extent.
Drives quite smoothly at 80 mph (downhill in Montana, of course).
2. At low speed,  I've noticed an audible "screek, screek" type sound,
emanating - I belive - from the front left portion of the car. It does not
sound like metal on metal or like anything grinding, more like wet sneakers
on a smooth floor. The noise is much louder when making sharp turns and its
speed varies directly with the speed of the vehicle.
3. Wear on the right front tire seems normal.
4. During my trip, I did plow into a snow bank at a fairly high rate of
speed (packing snow into every nook and cranny of the front suspension).
Could I have bent something that would cause the tire wear but otherwise
not affect driveability?

Any suggestions?

Paul U.