The manual says you can put 225/50/16 on the rear but not on the front.
According to my calculations the circumference is no more than the stock 205/55/16. The wheel offset is the same on both the 16 and 17 inch rims and the circumference of the 225/45/17 is more than the two above sizes. Then why does MB not list the 225/50/16 as okay for the front?

Thanks for any and all answers.

It is probably because when the fronts turn, they would hit the fenders or chassis.