Just replaced my rear pads and rotors with 53,000 miles on the originals. Front pads were replaced and rotors turned at about 48,000. Mixed highway and city driving. Neighbor across the street told me the rotors were fine, he used to be a metal model maker for GM before he retired. I replaced the rear rotors though because I had new ones waiting to go on. Motorcraft up front and Wagner Thermouiet pads and Centric rotors in the rear. First time doing my own brakes and only took me a little over two hours with all the lug nuts being stuck (Belle Tire torqued them too tight) and the passenger side rotor was stuck on.

 

I changed mine about a month ago on my 2005 FX4, had 52k on them. I could've probably gone another 10k but I went ahead anyway. The back were pretty close to the end of their life but the front had a bit more life in them.

 

I'm at 112K on the stockers. I got my truck with 72k and have done mostly highway since then and maybe 10%city with the occasional offroad drive. No hauling or towing with it either. Brakes are next on the list once I get the ball joints and tie rods done and save a bit more money.