Hellyeah will headline on Friday Aug 7 and Down will headline on Saturday Aug 8. The show takes place at the Birch Run Expo Center in Birch Run, Michigan.
Tickets can be purchased here: http://www.dirtfest.com/2015/tickets.html
For up to date info on what bands are performing on what days, check out the Dirtfest website here: http://www.dirtfest.com/2015/