I have Centra wheels on my 300SD with 235/55/16 tires.
I wanted to get it close to the stock 195/75/14 tires.To do that I would have to put 205/55/16 tires. I have that size on my 2001 TDi New Beetle. It looks like it would be way to small for that rim. Does any one run that size tire on a 16" rim? Thanks

you are correct on the 205/55/16 being very close in rolling radius to the stock 195/70/14 tire. within 1/2 percent. now to you question. what is the width of your 16 inch rim? if it is 8 inches or less, the 205 cross section should fit. to be sure, go to tire rack and pick a specific tire and see what the tire manufacturer recommends for rim width. varies slightly from manufacturer to tire manufacturer.

Anyone know how wide the Centra 16" wheels are?
I hope I don't have to dismount a tire to find out.

should be stamped on the rim somewhere. look it over carefully.