The rear D407 on my 09 Road Glide started the "cupping" just like the font did. I called the HD customer service line, they gave me a ticket number as told me to take it to any dealer and have it checked. The front was replaced by the dealer at 6K miles, took it in today at 10.5K on the rear. They checked it out and ordered me a replacement under warrenty. They told me it appears to be a heat related problem, as soon as the weather got warm, the tires started "cupping out" they had replaced several. The dealer is Shenandoah Harley Davidson, in Stanton, Va. GREAT folks to deal with!