Get vector and vector magnitude

Hello! yet another question, i’m trying to remove any auto wheel expression from y rigs. At the moment i use world vector expression based on previous frame positions to drive wheel rotation, it works fine but still an expression.

i try to convert my expression into some native mathematic nodes graph but even i have vector operators i can’t figure out how i can extract a single vector direction and magnitude to drive the wheel rotation. Th goal is to compute an unique vector that will be a generic base value to compute wheel rotation.

Thx for reading!