[davidelectricred]

I have an '06 330 with I-drive. I took it into tires plus just to get a simple inspection. I do so every few months because the car is out of warranty and I'd like to know what issues are coming up. They told me that my rear rotors are below the man. Suggested point. I find that strange because my pads are fine, I-drive says I have 17k miles until I have to worry about my rear brakes.

So should I be concerned and try to handle it ASAP?

[PINeely]

If you haveva caliper, measure them. How many miles on them?

[username604]

Originally Posted by davidelectricred

I have an '06 330 with I-drive. I took it into tires plus just to get a simple inspection. I do so every few months because the car is out of warranty and I'd like to know what issues are coming up. They told me that my rear rotors are below the man. Suggested point. I find that strange because my pads are fine, I-drive says I have 17k miles until I have to worry about my rear brakes.

So should I be concerned and try to handle it ASAP?

well, if the rear pads were replaced before without the rotors being replaced, it would make perfect sense that the rotors need to be replaced before your current rear brake pads.

you can drive with thin rotors without immediate danger, but they should be replaced when possible

[superjay]

when they get thin they are more susceptible to cracking due to excessive heat and temperature changes. If you do not drive it too hard I wouldn't worry about it. Once a rotor cracks it becomes dangerous. if it cracks it can shatter in an emergency situation.

[Efthreeoh]

Take into consideration that tires plus is looking to sell you a brake job. Since these are the rear rotors there is not such an urgency because the minimum thickness spec has been reached. The most economic choice is to replace the rotors when the pads need replacement. This choice would have little compromise on safety as the first sign of failure would be warped rotors. If you are not tracking the car, then the possibility of overheated rotors that would lead to cracking and a catastropic failure of the rotor is so extremley remote it is not even worth consideration.

Rear brakes on most cars only perform about 20% of the braking action, E90s with brake force distribution, maybe a little more than 20%, but the chance of the rear brakes completely failing is near zero.

The most likely scenario as posted above, and counting that the CBS says the rears are due for new pads in 17,000 miles, is the rotors are on their second set of pads and have reached the minimum thickness spec.

Did you ask how far under the spec they measured?

[Surly73]

Something important to note that's come up as a discussion point on several BMW forums I've been on:

The stamped "minimum thickness" does not necessarily mean that as soon as they reach that thickness you must replace them. It means that if you're doing a brake job and the rotors measure less than the min thickness they must be replaced at that time and not used for another set of pads.

Generally, I and all the other DIYers I know replace pads and rotors every time a brake job is done because the rotors will definitely be below min thickness by the time a second set of pads would be used up. In later conversations the above issue came up, and it looks like it would be perfectly "within spec" to run two sets of pads for every rotor and you'd be just fine. Assuming you are buying OEM/OES and not going to a dealer, the cost of rotors isn't that high, however, and there's some peace of mind in replacing pads and rotors every brake job. This is especially true in rust belts with lots of winter salt use. No matter how much painting, priming, anti-seizing I do my rotors look pretty nasty by the time a pad change comes up and I'm happy to get new ones. Of course I only need brakes every 5-6 years so that's 5-7 salty winters.

[davidelectricred]

Originally Posted by Efthreeoh

Take into consideration that tires plus is looking to sell you a brake job. Since these are the rear rotors there is not such an urgency because the minimum thickness spec has been reached. The most economic choice is to replace the rotors when the pads need replacement. This choice would have little compromise on safety as the first sign of failure would be warped rotors. If you are not tracking the car, then the possibility of overheated rotors that would lead to cracking and a catastropic failure of the rotor is so extremley remote it is not even worth consideration.

Rear brakes on most cars only perform about 20% of the braking action, E90s with brake force distribution, maybe a little more than 20%, but the chance of the rear brakes completely failing is near zero.

The most likely scenario as posted above, and counting that the CBS says the rears are due for new pads in 17,000 miles, is the rotors are on their second set of pads and have reached the minimum thickness spec.

Did you ask how far under the spec they measured?

I didn't ask how far they were under, but he didn't say I was in any immediate danger. Like stated I'm on my second set of pads to my knowledge. I bought my car CPO and only had a brake job once. That definitely sounds responsible to get the rotors and pads done at the same time.