What shaft length at 7.5x17H2 ET37 and gauge widening?

Hello, I bought for my C-Class (W203) 40mm track width (20mm per axle) incl. ABE. (http://www.ebay.de/itm/380736961025?…) Since I need new wheel screws, I have just measured my current ones. I need the following screws: M12x1.5 ball bundle. The shaft length is about 40-41mm. Is it now that I simply add the width of the track plate and finally order wheel screws with 60mm shaft length or should I safety be 56 or 59mm Does it seem a bit strange to me, because there are still track plates for my model with 30-35mm widening per side, but I can no longer find longer longer wheel screw offers. I would like to have a look at the following offer:http://www.ebay.de/itm/201205947148?… Many thanks in advance