If you look to the parts you will see that the control arms and bushings on a 500E are the same as a 300E with 195/65R15 tires.
I would suggest that the suspension was designed for these tires.
Probably the most important point I would like to make is reguarding the CONCEPT of aligning an automobile. I don't believe that setting a car up to a specific number is aligning a car.
I see it as an art like playing music by ear. The numbers are a guide and the performance the answer. If you can not get performance within the numbers the rest of the job is to take the numbers and find the problem. THAT in total is what I call aligning a vehicle. From that definition you obviously haven't had your car aligned yet.
Back to the tires. Whether MB adds enough structure and stability to their front ends to take the massive change in loading your tires give, is debatable. That they do change the loading and its effect on prformance isn't.
It is an absolute fact that the tire size you have on that car will cause you grief in this area forever. When the tires are new there will be less effect, but as they grow different from use you will wind up with what you are seeing.
And how anone aligning a car could overlook CASTER is beyond me. Especially a car that has questionable angles due to a collision. Aside from the regular angles CAMBER, CASTER, and TOE some others should be used to evaluate a continual pulling condition on a wreck repaired auto. One should look to the set back and wheel base also and the steering axis inclination and included angle. Camber is the sum of the included angle plus steering axis inclination. If Camber is OK on a vigin car the other two are bound to be OK but a sum that is the same from different components will add up to your type of problem.
The point is to be able to read and visualize what is the problem when it all don't work. THAT is an ALIGNMENT!
Bosch Master, ASE Master, L1
33 years MB technician