My front end, despite an alignment a few months ago, has pulled to the left or right depending on road crown and other mysterious factors. I wasn't too concerned about it since the guy at NTB told me that it was probably my winter tires. They came with the car and this is the first time I have had to use them. The area where the sidewall meets the tread is unusually worn. I knew the old owner and he did not corner hard or beat on the car. Now the steering wheel has begun to turn slightly back and forth in a violent sort of way. Can this be attributed to the tires, or does this sound like a more serious problem that will ruin my day, week, month?