I have a 2007 Nissan Versa model S. The car operates in normal fashion, but when driving above 30 m.p.h. and braking is needed, the car vibrates and the sensation can be felt the most through the steering wheel. The car doesn't do this when I simply decelerate, it only does it when I brake and again, I have to be going about 30 m.p.h. or higher; once I'm braking and the speed reduces, the vibration reduces and then stops altogether. Could it be my rotors, or may I be looking at something more severe? If it helps, my car was aligned and the tires were changed and balanced in October 2010; this still didn't correct the problem.