Just about got 75,000 miles on my 19.5 inch tires. Still can sink Abe's head in the tread so figure I have a few thousand miles left but my highway travel across the continent and the evil DOT folks are a concern. After much research and deliberation on my options I figured it was time for some new tires. Ended up buying 6 new Continental HDR tires since they have proven themselves so well on the first run.
Went to the dealership to pick them up and good golly, the price of these things is beyond ridiculous!