I replaced my pads at 39 months (around 65,000 miles) because two of my pads were separating. The friction material in two of my front pads was separating from the metal backer and I decided to replace them even though they still had A LOT of life left based on the thickness. If there were no physical issues they would probably last 200,000 miles. I replaced them all with NRS galvanized brake pads, which are also put together in a way that they friction material will not easily separate from the metal backer. Cost $158 for the fronts, $158 for the rears. Still going strong today at 146,000 miles and will likely never have to replace them again.