12/9/17 THERE WAS A SMALL AMOUNT OF SNOW ON MY DRIVEWAY. MY DRIVEWAY IS SLIGHTLY ON AN INCLINE AND THEN LEVELS OFF AT THE TOP I PUT MY VEHICLE INTO 4 WHEEL DRIVE AND PROCEEDED UP THE DRIVEWAY WITH NO PROBLEM. I DEACTIVATED THE 4 WHEEL DRIVE AND PLACED MY VEHICLE IN PARK W/O USING THE E BRAKE. I NEVER USE THE BRAKE WITH THIS VEHICLE OR MY PRIOR VEHICLE A TUNDRA. TWO AND A HALF HOURS LATER MY DAUGHTER INFORMS ME THAT SHE HEARD A LOUD BANG AND OBSERVED MY VEHICLE HAD ROLLED DOWN THE DRIVE WAY STRIKING A TREE. WHEN I WENT TO INVESTIGATE I OBSERVED THAT MY VEHICLE GEAR SHIFT WAS IN PARK. ALSO THERE WERE TIRE TREAD MARKS ON THE GRASS AND NOT SKID MARKS. QUESTION IS WHY BEING PARKED FOR OVER TWO HOURS THIS OCCURRED.