Hi, I'm Tim west. Do you hear and noises in the front end at all? Check tires for cupping, or any irregular wear. When was the last time you had an alignment and balance?

sounds like your tires are bad. either a belt has shifted, or the internal structure of the tire has broken done. in either case you need to replace them. and yes, do check the alignment!! the balance should be done at the time the new tires are installed. being that the car is already 11 going on 12 years old, don't be surprised if there are some front end parts that need replacing too, your alignment mechanic will alert you of such repairs.