I have a 2004 audi a6 2.7t s-line sedan with 56,000 miles on it. for the past several months it has had a severe shuddering in the steering column as i accelerate mid-throttle, as when i accelerate onto an on-ramp. i have tried to have my local audi dealer address this (it is a certified vehicle) but they so far have not come across with resolution. i have also contacted the audi of america customer support folks several times and they say that there is not a problem like this with this car, but they also say that if i use a specific make of michelin tire, it might alleviate the problem! i'm concerned about the safety of this car-it doesn't always do this, but when it does the steering wheel "shudders", like it vibrates/wobbles and the whole car vibrates. it started at about 40,000 miles and seems to have worsened over time. is there a common problem with this vehicle? please help if you can! *tr