I do quite a lot of motorway miles, and my front pads have been on for 45,000 miles so far, at my last service Honda told me that the front pads were 80% worn, and should be replaced, and the front tyres were down to 2mm.
When I had the tyres changed I asked the tyre fitters to give me a price for the pads, and they said they are only 60% worn, "Theres still plenty of meat on them".