There is no upper balljoint on this model.
My understanding is:
Wider tires have more rolling resistance, particularly significant at higher speeds. The CA bushings give more under the higher load. This leads to a toe out situation with standard alignment parameters.
The offset would increase the 'leverage' of the rolling resistance.
You may need to set the toe in a bit more to get even wear with wider tires.
This assumes there are no component level issues, of course...
1986 300E 5-Speed 240k mi.