My strong advice is as follows. Realize that I've driven the SD over 50K miles on 215-70-14's.

The 14 inch wheels are NG for this vehicle with larger tires. However, the smaller 195's look ridiculous in the wheel wells.

So, if you go with larger tires, the vehicle feels like it's riding on water balloons. But, you still get the lousy ride.

The solution is to get rid of the Bundts. Find a set of 15" wheels from the later W126 bodies ('86-'91). You can usually find four of them for $150. or so.

Install a set of 215-65-15's and you'll thank me after you do.