For about the last two weeks, my car has had a bad vibration. The car is fine when under 45 mph. At 45, the steering wheel starts to shake. At 50 mph, the wheel shakes like hell. And then it smoothes out again once I get above 55. I started noticing this when I installed new wheels and tires, but since it isn’t all the time, I don’t think the wheels/tires are the culprit. I think the wider tires I put on just emphasized the vibration. I think it’s the steering because while I’m going around a corner at speed (like an on/off ramp) the whole car will twitch to the outside without the steering wheel moving or the tires loosing traction. I recently had it into the shop for a 4 wheel alignment, I told them about the vibration, but they were clueless. Anybody have an idea of where I should be looking? Any help is much appreciated.