Steering wheel vibrates when brakes are applied

BMW is by far the worst brand in the world for their employees insisting only their original parts are acceptable. They think only their over-priced parts should be put on their cars. The truth is there are a lot of conscientious aftermarket parts manufacturers out there and there's nothing wrong with their parts.

In this case the clue is the new front tires. While warped brake rotors IS the most common cause of what you described, it is definitely not the only one. When the wheel is removed, it is possible for rust and scale to fall between the rotor and hub making it wobble as it rotates. You're more likely to feel that in the steering wheel at higher speeds, and less likely to feel it in the brake pedal. This is called "lateral runout" and it makes the brake caliper tug back and forth as the wheel rotates. This also commonly occurs with cast wheels. They corrode and pieces break off and stick to the rotor when the wheel is removed. When the wheel is reinstalled that piece gets stuck between the wheel and rotor and makes the wheel wobble.

Another common cause of a brake rotor that suddenly warped is the failure to use a click-type torque wrench. We used to just run the lug nuts on with air tools but that has been totally unacceptable since the early '80s. Every manufacturer specifies the torque that will keep the wheels tight, loose enough to change a flat tire on the side of the road, prevent damage to nuts and studs, and most importantly to maintain even clamping forces all the way around the wheel. When the nuts aren't tightened evenly the uneven clamping forces put uneven stress on the rotor that can show up right away as a brake pedal pulsation, but usually shows up after the rotors have gone through a few heat-up / cool-down cycles. All tire and alignment shops have wall charts showing these torque specs for all cars and light trucks. Dealership mechanics have them memorized because they see the same car models every day.