(solved)
Im just beginning with unity, and I’m trying to model an electric wheelchair. The rear wheels should work like in a car so I’ll propably manage those following tutorials, but the front wheels should follow the motion and spin freely 360 degrees and of course roll too. I managed to attach forks for those wheels with a hinge joint and I guess (?) I maybe should use another hinge joint to attach the actual wheels to forks. But then I dont really have any glue on how to set the colliders. Is that even possible with unity to have those front wheels spin and turn based on friction or would I need to script all those physics my self somehow.
Oh and I hope I can assume that having rear wheels spin at different speed will make this thing turn without explicitly changing steerAngle of front tyres like you would if it were a car? I’m kind of frustrated with the documentation available. Would be a lot easier if I could read how the physics are actually implemented in unity. Now it’s just a lot of guessing.
Edit:
Now its kind of working with sphere colliders on front wheels (I guess I should rather use custom mesh colliders later) and wheel colliders at back. But its not working well, so ideas for improvements are highly apreciated. The biggest problem is with how the forks are connected to the body with hinge joints. The joints wont really stay fixed, they bounce a bit around the position they should stay locked to and cause the whole thing to bounce around quite wildly. Is there a cure for this?
Edit:
With configurable joint it’s working again bit better, but still it’s bouncing around. Also the wheels are somewhat sunken inside the ground though the colliders have the same size as meshes. What could be the reason for that?
Edit:
Remembering to use brakes on rear wheels definetely helps… 
Also found some more documentation. 
All seems to be pretty much solved for now.