I have about 5.5 mm left on both the front and rear pads and I have over 50,000 miles. That seems like a ton of miles for brakes. How low can you go before they need changed? Will the car letme know with a warning light?

 

the car will let you know with a warning sound. brake pads have a metal tab that will rub on the rotors when your pads get low. when the brakes start squealing, it's time to change the pads

 

150k+ miles on a set of TSX brakes is not unheard of.

You'll know when it is time. You will hear n awful squeal when you apply the brakes - not the "car sa for a while squeal" but a loud, obnoxious noise that sounds like metal on metal (which is what it is.)

 

Yeah you will hear a squeal. I think 2mm is when you should replace.

 

There are two major factors that determine how long the pads will last (all things being equal, meaning comparing apples to apples). Driving style and the type of miles you put on them. Easy on the brakes and all highway miles, and they'll last forever. Use them often and hard, and drive around town a lot, then not so much. Fortunately, they're a cheap and easy swap, so I can't see that it makes much difference either way.

 

changed the rear brakes for the 1st time at 150K miles but still on the original fronts.

 

Pads are cheap so just replace if u question it. IMO