Well, standard on the 123 Coupe was 195 tire, nothing else. 205 wasn't included in the original setup. Problem is, that with wider tires you increase the stress on the front axle. Not so much the bearings, they are pretty solid (pretty much the same as in the 116 and 126), but the rubber bearings of the lower and the upper arm and, to the most part, the stearing box. And that is a pretty pricy item.

In general the front axle of the 123 is not one of the solidest construction Mercedes ever designed.

If you look at the topspeed you gained take into consideration that you usually have a 7% tolerance at the speedometer. At least.

Kind regards
Eberhard