My wife drives a 1996 850 turbo sedan (known as a Platinum). I have a confusing problem and desparately need some education. While driving the car recently I noticed both steering wheel vibration and a pulsating brake pedal which occurs around 40 mph and at highway speeds. My wife claims these problems have been present ever since we had brake and tire work in the fall (2001). The work consisted of installing the mounted snows and rebalance(I conceded to rebalancing the snows since they only had one seasons use), additionally the front brake pads and rotors were replaced. Interestingly the rotors were replaced with an aftermarket(German) rotor which our mechanic recommmended. So now the car is back in the shop and our mechanic is recommending install the summer wheels and tires to see if the problem clears up, suspecting one bad tire. These winter tires have only two winter seasons use. What do you guys think - wheel, tire or rotor problem?

Seeking some education,

John