Hello! I have a an E350 Sport Premium with airmattic suspension all round, and with 18" stock alloys as per image. I would like spacers front and rear so that the wheels fill out the arches as I hate the sunken in look. I would like the wheels as close as possible to the fender but without the worry of the fender touching the tyres if the car drops if the car malfunctions due to airmattic. I would really appreciate anyone who has the same car on airmattic that has used spacers and can give me any advice on what width I should be looking at front and rear. I've watched youtube to try and determine the width but its tricky - not sure if i need 10 or 15mm front and whether i need 15 or 20mm rear. Help - many thanks!

My E350

 

I would go 15 all around.