I replaced the original Scorpions on my 08 Expedition just before 40,000 miles. I thought they had a little left on them and would have pushed them to maybe 45,000, but the wife started complaining that I wasn't taking care of the things that needed to be done when they were supposed to be, so I put them on to shut her up. I also had to replace the rear brake pads like others have been saying at about 30,000. I too thought that it was strange the rears were shot and the fronts were still fine.