Some of you know I took my 09 prius in to get looked at. We purchased it with 52k miles on it and they have brand new, never been driven on tires on them... We brought it back in because it was going "Vvvvvt....vvvvvt.....vvvvvt..." that would get faster and louder with speed increase, but on the drivers side, enough to feel the vibration of the sound in the gas pedal. I took it in, they said they checked the brakes, the tires, the wheel barring, nothing was wrong. They rotated the tires and told me nothing was wrong and that the sound I was hearing was tire noise and that once the tires 'broke in' some they would stop making the noise. Car is under warranty and I'm still within my return guidelines. I've put brand new tires on many cars and never ever heard this before. Anyone care to fill me in on what could be happening here? Are they right?