You should change your BMW brake pads after 15,000–25,000 miles if you drive dynamically or 40,000–50,000 miles if your driving style is mild and you drive on the highway a lot. The brake pad thickness is also a good indicator – brand-new BMW brake pads are around 10–12 mm thick, so when they are worn down to 3–5 mm, it’s high time to change them.