Query on recommended tire pressure and weight front to rear?

The door card recommended tire pressure is 29 PSI front and 35 PSI rear on the 560SL. The weight distribution is heavier in front, about 55% front 45% rear. I thought that tire pressure should be directly proportional to load. So perhaps there is insightful expertise on this board to explain why the heavier front gets the lower pressure?

To add to this mystery, my 450SL door card said 32 PSI front and 26 PSI rear, with an approximate weight distribution of 57% front. So what is the basis for the OEM pressure differentials between front and rear across the 107 series? Anybody find good results with different sets of pressure?

Thank you for your ideas.