My 98 SVT came with 205/55/16's.
My next set was 215/50. They made my speedo read about 5 mph too high at 60-70 mph.
next set was 225/50. My speedo is back to normal and reads perfect. Only small rubbing issue on the back inner liners, but my car was built before they revised them.
You be the judge
I recommend the 225's