Did your Edge come with a trailer Hitch? If so, maybe the towing package has stiffer rear springs? Just something to think about. We had a 2013 Edge Limited and traded it in for a 2014 Edge Limited, both had the 20 inch wheels. Our 2014 Edge Limited rides so much smoother than the 2013 did, according to Ford they were no changes between the 2013 and the 2014 model years, but i say they were