What would cause the Passenger side rear tire to wear heavily
on the outside?

1991 300TE.

I would like to fix anything needed prior to taking
it to the indy for a 4 wheel alignment.

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81 Mercedes 300SD 289k.......SOLD
82 Mercedes 300CD 252k......slow ride

82 mercedes 300 SD...mi Unknown
83 Mercedes 300D ????ksniff..gone too
84 Mercedes 300D 148k........SOLD
85 Mercedes 300TD 386k and holding some one elses project

Any noticeable positive camber?

Not that I can tell.
Would that be some kind of an adjustment
or part replacement issue

__________________
81 Mercedes 300SD 289k.......SOLD
82 Mercedes 300CD 252k......slow ride

82 mercedes 300 SD...mi Unknown
83 Mercedes 300D ????ksniff..gone too
84 Mercedes 300D 148k........SOLD
85 Mercedes 300TD 386k and holding some one elses project

About 5K miles ago, I was hearing a creaking noise from the left rear of my TE. If I sprayed silicone onto the spring link (trailing arm?) bushing, noise went away. So bushing is deteriorating.

Recently, I noticed abnormal wear on the outer and inner edges of the left rear tire. Tire pressure ok, and other three tire wear normal. I removed the wheel, and the left wheel carrier bushing looks bad, with badly cracked rubber. The rubber on the other four suspension links look ok.

I suspect both of those bad bushings affect the camber when the car is in motion, and causing that abnormal tire wear.

I do not have the correct bushing extractor/press in tools, so I may buy a complete spring link (trailing arm?), and take it to the Indie to also replace the wheel carrier bushing

Hey Jack,
You don't say how many miles are on the car! 12miles? 1200 miles? 250,000 miles?
Sounds like you have identified most of the problem, bushings and links. Don't waste your time replacing the bushings, replace ALL of the links. If your rear suspension is original and I would bet that it is, then it is past time to replace the "ball joint"/"swivel joint" that the rear wheel carrier and all of the links connect to. The 124 is a great car but at 21 plus years they do need some major suspension work. You don't say how the car handles on the freeway, does it get squirrelly when trying to drive in a straight line. Feel like you are always chasing it with the steering wheel? The german rubber will look good but be bad. If the suspension is original, time to rebuild it. If you try to do it a piece at a time, you will always be working on it and your alignment will never hold.

I support the idea that one link is damaged , certainly the top one;

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Keep us posted especially if your problem is solved
Present cars:
My car: E-class 420CDI, 2008, W211, V8, 180 000km

Wife's one: C-class 220CDI Sport Coupé, Euro, 2002, W203. 345 000km

Son's one: GLK class 220CDI, 2009, W204

Sold E class 260E, W124, 1988 beloved car sold after 489 000 kilometres of reliable services (engine M103, clutch and 5 speed manual gear box all original).

E-class, W210 320CDI, 2000[/B], 225 000km, Sold