New pads are usually between 10-12mm in thickness. If the pads are worn down to about 3mm, you should start considering to change them.
New pads now comes with new material which will give you a high-pitch tone when it is wearing down. You can also try to determine by how much have you driven since the last pad replacement.
For many cars with alloy rims, you can check the thickness from the outside. If you can't see, then you need to go under the car and look at them that way.
I upgraded by pads 2 years ago, at that time I drove about 45k km, and I still have 50% left on the old pads. Based on that, I think a new set of pads should last at least 65k KM.
Philip |