check that tire pressure is adequate and even from side to side (front to back should be diff as per OEM spec).
then, take car on a level road (no ruts, bumps, etc) and test braking. If you're still pulling, bring the car in. This is a very black and white matter. A properly set up car should not pull to either side when braking. If it does, it's not correct.
BMW : Sine qua non
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