I am starting to look for some new wheels for my 2012 cvo street glide. I know it comes with a 18" rear wheel but I was talking with a buddy today and he said Hogpro told him to go with a 17" rear wheel on his SG. Can somebody explain the benefits of going with the 17" rear instead of 18"? I have 12" Arnott air ride on the rear also. Thanks!