Exceeding 5ms Magnitude causes strange random Wheel Collider friction spikes. Unity 2017.1 Default values. I was adding wheel slip FX, tyre smoke, skid marks, sound and came across this odd issue which I think is a bug since it starts occurring exactly when the Rigidbody is at 5ms+ which seems like some hard coded internal value. Nothing I tried would fix it, I believe this is an engine bug. In the following video pay attention to the 'Mag' value when it is above and below 5ms and how the wheel behaves. I added the white bar to the wheel to contrast the wheel pose behaviour so its more visible. In the top left are wheel slip limit values, they highlight erratic nature of the forward friction.