Try the following:
- Some parts of the maps collision are not the best, does it float in other places too?
- Center to world the main node with the spawn name on
(Most likely the fix) try resizing the wheel collisions only so the mesh sits outside of them more. IE select all 4 wheel collisions and size them down slightly. Make sure you turn off the pivot or it'll move the collision inward. to where the tire hangs out of it slightly on [wheel_lf]