Check for build-up on your wheels. I had the problem earlyer this year, took it off, and cleaned it out, worlds of difference. They may be balance but the buildup throws it off, easy, and cheap problem to fix...
If you look at the tire tread on that tire and it has like a curve in the tread it broke a belt but if not then it needs an alignment.//content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif