Back-in, always. As a Pvt E-1 back in 1985, I parked a Deuce-n-a half, front-in, at the barracks. Top was standing outside having a smoke. As I walked by he asked "Private, are you going to leave the vehicle parked like that?" I replied "No Top" and went back to the vehicle (not knowing what I had done wrong). After a minute or so of examining how the vehicle was parked, it dawned on me that it wasn't 'Combat Parked'. I turned the truck around and backed it in hoping I had chosen wisely about what needed fixing. This time when I walked past my 1st Sergeant, he pulled a valve-stem remover from his pocket and said when I came out of the barracks he would have handed me a bicycle pump to air-up the flat tires. (Doubtful that a bicycle pump would have been able to pump up the tires on a Deuce-n-a half, but knew I was going to spend hours finding out.) Been 'Combat Parking' every vehicle I drive ever since.