I'm North of Nashville. Been out to LBL (Land Between the Lakes) a few times. They have 2500acre ORV trail network that you need a pass to use. Once you sign in at the South Welcome Station, they provide you with a map of trails. It shows all the different trails and their difficulty levels.
Used my TJ Sport (D44 rear / 3.73 and BFG 30" all terrains) on the moderate trails. Haven't tried the hardest trails yet. My roommates JK Rubi Unlimited tore through the hardest trails on a later trip.
It's a great place to spend an afternoon.