Not saying this is the same, just more info for the topic.....
My Supra was tight, newish and handled extremely well when I first got her. As the tyres wore down, it developed a nasty scary sideways kick at the back end every now and again when driving in a straight line in the wet. Motorway speeds were the worst, but it was almost unnoticeable in the dry apart from manhole covers. The rear tyres were found to be almost bald on the inner third but legal on the outer two thirds. I had the camber adjusted and new tyres, and the problem was gone never to reappear, even when the next set of tyres were close to worn out.
Edit to add that CW seems to have an answer...
http://www.mkivsupra.net/vbb/showthread.php?t=89069