when do front brakes need replacement

Typically brake pads are replaced based on wear, not miles. I would have a shop check the brake system if you are concerned about it.

There is a metal striker on most brands of pads that will scrape against the rotor when the pads are worn down. The sound will range from nails on a chalkboard to a squealing as if a wheel bearing is going out! This is your warning device! I usually inspect and when thickness of pad gets between 1/8 to 1/16 Of an inch change them out assuming the caliper piston is pressing it evenly across the surface of the rotor! My Sequoia wears it unevenly due to a sticking piston causing me to change it at 1/8 inch on back side where inspection hole is located but on front side it is usually thinner. Better to replace pads for less than $40 than to gouge and tear rotors up and have to replace it with a new one! Front pads will wear 1 1/2 times faster than rear disc brake pads ! They (front) absorb more mass and energy than rear pads, your driving techniques also play into how long your pads will last too! I prefer semi metallic pads, metallic too agressive and ceramic too expensive! Hope this helps. papa ( i got to go fix that caliper)