So, I actually thought about that, and made sure to represent each wheel with a 2d plane, modeled in just such a way that the cylindrical physics bounding box should fit perfectly on the wheel. It's highlighted in the left.
I put this whole thing together in over a year or so of development, and intend to have it so that it can actually be entered, as it's part APC. What you're currently seeing is the cameras, joints, and links between each. There's over a hundred which had to be filled out and linked by hand. Think that the lower quality meshes will work?