Is it really a vibration or is it the increased road feel caused by a low profile tire on an increased wheel size. The original size on your car should have been 185/65-14. Now you are probably using a 205/40-17. Your old tire had 4.75 inches of rubber between the wheel and the road your new combination gives you 3.25 inches of rubber from the wheel to the road. The decrease in rubber will make you be able to feel every bump and crack in the road more, it may be felt in the steering wheel. Especially if struts, ball joints or tie rods have any wear in them which would come with age or mileage. An alignment shop will be able to tell you if you have any of these problems. I would highly recommend an alignment when upgrading tires anyway.Try another tire shop you may have defective tires, up-sized wheels also are easier to warp.