Jump the dirt bike into the mansion grounds in Ep. 10: Legacy
Battlefield Hardline DARE DEVIL Achievement / Trophy Guide
Just before the mansion at the end of mission 10, you have to walk to the far right of the path to a ramp. The Dirt Bike is placed perfectly so you just have to drive straight and hit the ramp to jump into the front yard of the mansion. After you land the achievement / trophy will pop.