If the tread is fine right up to the edge where the worn area sharply drops off from good tread depth to almost no tread depth, I would not suspect that negative camber has caused the uneven wear, especially not that quickly. Negative camber alone WILL wear the inside edges faster, but the wear is spread quite a bit. Perhaps as much as 1/3 of the tread on the inside will be progressively worn more towards the edge where you'll get a square corner on the inner tread block. I've been running -1° to -2.2° negative camber on one of my 240s for about 4 years. With proper toe (slight toe in, I run 0.12° toe-in), negative camber does not cause rapid wear.

In my experience, excessive toe in either direction will cause rapid wear on a narrow section right at the very edge of the tire. Toe-out will cause the inner edge to scrub while driving straight. On a stock 240, which has very little camber, the tire is upright so it tends to just wear a small section right on the edge. This wear can happen very quickly if the toe setting is way off. If you have bushing or tie rod or steering rack wear, it could have enough play that the toe is not always the same while driving.

My experience with excessive toe-out started when I drove over a curb in my 240 about 7 years ago. With toe-out, each front tire is trying to go in opposite directions. I had fairly new 185/70 all season tires on the front with a wear rating of about 600, so they were very hard. For 3 days I had to drive the car while I waited for the replacement control arm & strut to arrive. In that time I wore the inner edge of one tire to almost nothing, and noticably wore the other front tire. This was an extreme amount of toe out, such that the car would struggle to go straight at 45mph.

If your car feels like it wanders on the road and if you take your hands off the wheel it tends to wander back and forth or pull to one direction, you've probably got an alignment issue that comes down to toe not being within spec. With too much toe-in, the car would track straight and wouldn't wander at all, but the outside edges would scrub and wear rapidly. With the toe setting off just a little, it will take a while to show on the tires. My suggestion would be to rotate the tires to the rear and keep using them, assuming that they are not worn to cord on the inner shoulder. The tires on the rear will get very little wear on the inner shoulder because of the solid axle, so you can still use them if they are still safe to use.
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forums.turbobricks.com

Uneven wear from outside to inside is usually a sign of a camber issue. Just in case, camber is the angle described by the tilt of the top of the tire either in toward the center of the car or out. Negative camber leaves the tire tilted in at the top causing the inner edge to wear faster. This is very common on lowered cars where there is no camber adjustment. It's a problem enthusiasts live with in exchange for better handling and there are camber correcting parts available for this. Contrary to popular belief, the 240s do have minor camber adjustment available at the top of the strut. If the car's struts were removed and not put back in properly, your camber may be slightly off, but I don't think the adjustment provides enough movement to cause the kind of wear you are describing in so short a time. To get enough negative camber to cause the damage you are seeing, a couple of things come to mind: If the forward control arm bushing is bad and this has resulted in the arm shifting outward, toward the outside of the car, camber can change. Also, if your spring is very weak and has sagged, camber can change. Park the car on a level surface and look at it head on. Driver's side springs usually sag first. If you can see a notable difference in the ride height from side to side you have a bad spring. On the extreme side of things, it is possible that the strut itself is bent, taking the entire spindle assembly with it. I daresay you'd have some other symptoms though.

DS