Originally Posted by
EEngr
"Make it fit" is one reason. In order to make it fit, the bogies need to be rotated forward, backward, or level in order to minimize clear the gear wells. Some consideration needs to be made for that operating mechanism. Once the gear is dropped and contacts the runway, the hydraulics that stow it now have to allow it to rotate one way or another about it's "ankles". The travel involved may dictate one postition (toes up vs toes down) over another.
That's indisputably true, but as an answer to the question it's back-to-front.
Yes, on some types the bogie needs to be rotated as the gear is stowed because when it's deployed it isn't level, as opposed to early jets like the Comet where it was and retraction was more straightforward.
But we haven't got any closer to explaining why bogies are tilted, let alone why the tilt is one way on some types and the opposite way on others.