Originally Posted by scottn2retro
I think part of the problem is the size of the front brakes vs. the rears. The front calipers/pads are huge compared to the rears and probably end up doing too much of the braking, while the rears have too easy a time of it. So one advantage of going with aftermarket brake upgrades is being able to get more rear brake.
The physical size of the rotors and calipers has little to do with "how much" braking is done by that particular set of brakes. Piston size determines brake bias. And I'm pretty sure that the engineers at BMW understand how to compute optimum bias.
The rear brakes do not do little braking because they're small. They're small because they do little braking.