A couple of things that i remember being there the first time. Like the tires would come off a bit slightly. Had the same problem with this monster truck game I made. I fixed it by lowering the wheel weight. The other thing I found but could never get it to reproduce is where tires started in the wrong spot. On top of the buggy instead of in the wheel wells.

While I never seen the second one happen in 6.31.4 (I think it was a fluke), I have seen the first one.

So in the end, nothign worth complaing about but nothing worth mentioing either.