Asking you modder's cuz I'm not a modder but, I do use the editor.
When I change the rim and tires sizes in editor and save for each...front and back, I then save the mod when I'm done editing.
The problem becomes that when that particular car is in my shop, sometimes they look like they have flat tires....where the tire is partially sunk into the floor / ground. Is there a setting for changing the elevation of the whole car so that it looks correct without flat tires?