There is no harm in using a dummy as your root bone if it is working but you dont need to reset xform for the dummy. We had to reset xform for the previous model because it came from another software and been manipulated, so we had to freeze all the transform information with reset xform. If it isnt too much work for you, you can follow this link hierarchy:
- Root Dummy
- Car chasis
- Wheel dummies for each wheel(positioned at wheels’ pivot origins)
- Wheel meshes
Link everything listed from bottom to top to each other and then export and see how it goes. Also make sure Z axis is set as Z-Up in export settings.