Pull off a front and rear wheel. Look at the top of the springs for the rubber pad. look for some nubs on the pad.
1 = thinnest
Rear only goes to 3 max I believe.
'92 300CE - Sold
2004 C240 - C7 Wheels
2015 ML350 - P1, Pano, Ash poplar wood, Sport Dinamica interior, Running Boards Keyless go.