I think some have done 38, havent seen 40, but I am not sure. I don't think it could necessarily hurt to try it.
I'm not a tech thgouh, thats just my opinion.
'92 300CE - Sold
2004 C240 - C7 Wheels
2015 ML350 - P1, Pano, Ash poplar wood, Sport Dinamica interior, Running Boards Keyless go.