Brake Pad Replacement--When?


My car mechanic said my brake pads are at 35%. When do you need to replace them?


Ask him. Typically it’s at less than 3/32 of an inch, but a lot depends on how evenly they’re worn, how many miles you drive, and what type of driving you do. If you do a typical 12,000 miles a year mixed driving, I’d plan on getting them changed sometime next year.

Or, consider how long it took you to wear off the first 65%, subtract 15% for safety, and estimate from there.


I’ve always wondered if the wear was a linear function. They seem to wear faster as they get thinner but that’s only based on my limited experience. I always attributed it to heat dissipation issues as the pads lose mass. I wonder if there’s any data available.


Interesting theory. I’mm not sure heat affects erosion of the material, but it may. My guess is that when they start getting thin we simply become more sensitive to the changes.


Well, I found something to support my theory:

Resins are organic materials used to bind and reinforce the different components of a brake pad. The resins act like a thermoset plastic, which holds the components together like glue. This glue forms the matrix of the brake pad. When heated, resins tend to shrink and crack, and at very high temperatures they may turn to carbon. Carbonized resins cause weakening of the matrix and accelerated pad wear.