I assume there is zero difference here in a 50 vs 55 except maybe an ever so slightly less harsh ride?

 

That's gonna be .8 inch taller and therefore almost 3-1/4% speedometer error change to the slow side (you will be traveling faster than the speedometer says), along with similar odometer error and a slight reduction in calculated gas mileage.

863 Revs/Mile vs. 835 Revs/Mile

https://tiresize.com/calculator/

 

well figuring OEMs are already 55s i'm not sure what you are getting at.

 

Aw dang, I didn't even think of stock size. And none came with tires 205 wide either.
185-55-16 was probably the stock size? 205 tires on that wheel width might look like little balloons, but doable.

Going from 185-55-16 to 205-50-16 the speedo calculation difference would be negligible, but since more tire contacting the ground there would be a bit harsher ride.

The 205-55-16 would be taller of course

 

205/50R16 and stock 185/55R16 are virtually the same not counting differences in tire manufacturers. I use this free online tool allot

Online Wheel and Tyre Fitment Calculator. Offset, Tyre Stretch and Speedo Error | Will They Fit