I had new tyres fitted a few years ago to my '87 740, and at the same time had the tracking (toe-in) set. The front tyres wore down on the outside edges far more than the rest of the tread, so I had the tracking rechecked at a different place.
In the past year I have replace all the front suspension bushes and steering joints, including the bottom ball joints, track rods (tie rods to you US citizens) with the inner ball joint, and the outer, track rod end joints. I then had the tracking reset. Then I swapped the front tyres with the rear ones, which wear evenly.
But after six months use, the outer edge - the first inch or so round the circumference - has again worn right down to near baldness on both fronts.
Steering seems fine (though I've often thought this 740 steers like a whale compared to a 240) with no play, and no pull to one side, and no tendency to wander.
The only thing left that I can think may cause this is that the camber is out of adjustment, but I think this can only be altered by replacing the stock suspension arms with ones of different lengths.
Anyone think of anything else that may cause this, before I try and find someone with a rig that can check the camber?