Its not the 15s to 16s thats the issue (aslong as the tyres are lower pro of course) its the difference in offset.
The dynamique alloys have an offset of 38 and this is what the car was designed to take, yet the 172 alloys have an offset of 48.
Therefore in theory you require a 10mm spacers.
If your car isn't lowered you will have no technical problems with running the alloys with no spacers, however aesthetically a 5-10mm spacer is desirable.
I have a set of 4 5mm spacers for sale, PM if interested.
Sam