The difference in the speedo reading will be much smaller, it's only 3.44%, so at 100kph indicated by the speedo you will actually have 103.44km/h.
But the speedo over-reads as standard, so most likely it will now show the correct speed.
But if you have lowered springs (or even standard ones that have gone a bit soggy over the years) the 205/45R17 tires will rub at full lock, but this also depends on wheel offset.
What offset do yours have?