I went from 15" x 7"wide rims to 17"x8 and now my car pulls to the left. What would cause this?

First switch the two front tires side-to-side and see if it pulls the other way. If it still pulls left, visit an alignment shop. Ford is notorious for building small cars that do not have provisions for adjusting "camber" to correct pulls and edge wear on the tires, but there are often some tricks that can be done to lessen the problem to the point you can live with it. Tire wear has always been a big Ford problem but their designs make their cars ride smoother than other brands so they use that characteristic to sell more cars. They aren't too concerned about poor tire wear after you buy the car.