It's not the vehicles wheels that are sunken, the wheels are absolutely correct, it's the *scenery* that is raised from the ground, and this to fix flickering when using multiple layers of custom ground, and each scenery might be slightly different because of many factors, but it's not really a GSX issue, it's more like a scenery issue.
It's not clear what do you mean with "black screen interruption". Do you simply had a pause for a moment, or a crash with an error message ? If yes, which message ? If it's just a pause but then the program continus normally, it's just your system that is catching up with memory allocation or similar.