it's normal for e36 to incline to one side, i.e. right side ground clearance is less than left side. 10mm seems normal to me. in fact if your check the rear ground clearance, you may detect a similar situation. it is perfectly normal and it is due to the weight distribution of the car. if the different is larger than that, then it may be due to 'tired' springs but you can check them by bouncing the car a few times.