Self-collisions when modeling wheeled robot

Hello fellow developers,

I’m currently struggling while modeling a wheeled robot due to the wheels self colliding with the chassis.
I modelled the vehicle in the exact same way as the STR robot example (see attached prim tree).
However, when running the simulation, the wheels seem to collide with the chassis collision element, which is not the case for the STR robot. Does anyone has a suggestion what I’m missing? I made sure that all prims are exactly configured as in the STR example.

Situation before running: Both STR and my robot are above the ground

After both robots hit the ground: My wheels left their initial position and are moved next to the chassis due to collisions:

The prim-tree structure (modeled the same as for the STR)

If the Karis_2019 prim is set up as an articulation you can make sure the enableSelfCollisions flag is set to disabled? You can modify this from the PhysX Properties panel.