Vehicle Physics - Tire intersection testing problem

[aughey]

I have a vehicle controlled using the standard Blender vehicle PhysicsConstraints setup. The issue I am having is with how Bullet is testing how the tire is intersection objects in the world.

I have a basic scene with a short cube that the car can roll over. When I drive up to the cube slowly, the wheel penetrates the cube until the center of the wheel is over the edge of the cube. At that point, the wheel jumps up suddenly. It seems that the intersection testing is being down in the up-down axis only.

The behavior I would have expected is for the car to provide some resistance when the edge of the wheel contacts the corner of the cube and drive up on the corner of the cube to the top. Instead, there's a sudden jump when the wheel is over the cube.

Is there a physics parameter that can be adjusted so that the object intersections are computed more exactly?

Thank you
John Aughey