Bullet vehicle

Ive got some questions regarding bullet vehicle nodes.
I am trying to use a Car collada model via assimp and apply a vehicle simulation. Now it seems to work fine so far, but i got problems aligning the wheels at the right positions.

As a starting point i looked at the contribution samples, and now I am wondering how the size of the box used for creating the vehicle has no (?) influence on the wheel position.
Is it possible to set the wheels position manually somehow?

yep, sure you do, otherwise just put another transform in between wheels and move them manually