Acceptable brake pad measurement?

[readytogo]

When I took my 135is to the BMW dealer they did a complimentary multi-point inspection and said my brake pads in the front had 10mm left and the rear 12mm.

When should the pads be replaced? mm - wise?

[Thunderguts]

That's a lot of pad left. I don't think a brand new pad has much more than 15 mm.

[tracer bullet]

Agreed, I was thinking 13-ish new but either way it's a lot. 15mm may be right.

2-3 mm is about where I'd start getting concerned. But it depends on how many miles you put on each year.

[MightyMouseTech]

Front pads normally have 12mm when new, and rears at 10mm. The pad sensor will trigger at 3mm, and is a good time to replace soon.

[readytogo]

Originally Posted by MightyMouseTech

Front pads normally have 12mm when new, and rears at 10mm. The pad sensor will trigger at 3mm, and is a good time to replace soon.

Thank you all for your info. It's good to know this before some Service Advisor gets too aggressive in their brake pad replacement recommendation

[tracer bullet]

It happens. I have a local indy that specializes in imports, even more so BMW's, and they wanted to change my X3's pads "because of the mileage". I own a caliper and found them to be around 6mm front, 8 rear. A bit early to worry about especially when I only put like 4k a year on it. Gotta stay alert even w/ shops you trust.

[NorthernDancer]

https://www.amazon.ca/Steelman-97844...483245&sr=8-17

I've been using the Steelman brake gauge for many years now. HPDEs demand 50% brake pad material so for the front, that would be 6mm or more. Even for just spirited street driving, I wouldn't want to go less than 4mm. 3mm is RED warning and should be changed immediately.

[fe1rx]

Originally Posted by NorthernDancer

https://www.amazon.ca/Steelman-97844...483245&sr=8-17

I've been using the Steelman brake gauge for many years now. HPDEs demand 50% brake pad material so for the front, that would be 6mm or more. Even for just spirited street driving, I wouldn't want to go less than 4mm. 3mm is RED warning and should be changed immediately.

It is always a good idea to advise caution but I look at it this way:

Each 1 mm of front pad represents about 2000 miles of usable mileage asuming you change the pad with 3 mm remaining. For the rears, 1 mm is about 4000 miles.

50% pad remaining is at the start of a track day. If I had spares at a track day, I would likely change them at between 2 and 3 mm remaining. If I didn't have spares, I would keep a close eye on the wear and stop lapping at 1 mm - then drive a half hour home on them.

BMW gives you plenty of warning at 3 mm remaining for a street car. Also, their predictive algorithm works remarkably well in my experience. For a street car you can comfortably go by that with the wear warning light serving as a backup sensor. Once you get the light, visually inspect the pads (because your sensor is only on one side) and then change the pads at the next convenient opportunity. Quite likely you can go another 2000 miles before the sphyncter needs to be concerned.

That said, I have disabled my warnings because on a track car they are just a useless consumable, given that I actually look at my brakes before, during and after each event, and towards the end of their life after each session.