this thread is of great interest to me: my '83 300D has always had both handling and tire wear "issues" that need both understanding and fixing. The facts are:
1) bad tire wear on the inside edge of the drivers side front tire (gone in 10,000 miles)
2) poor high speed handling - does not ride the 'rail' - likes to wander.
3) 4 different alignment machines ( shops) show perfect 4 wheel alignment.
4) oem alloy rims with 'H' rated tires for stiffer sidewall stability.
5) no obvious worn parts (lots of new stuff like upper ball joints etc)