Do I need a flange when installing an original 206 gti rim?

Hello, I have a question. 206 gti on my car is 17 inches. There were rims and they used flan when installing it. I bought the original 206 gti wheelset. Do I need to use a flange when installing the 15 inch 206 gti rim, or should I remove it? And the studs I use at 17 inches will be 15 inches, and I would be glad if you could help.

Studs are replacement
You do not need to remove the flanges, I have gti in me

the bolts seemed long to me, because if the width of the rim is 7.5 inches or the original rim, I would hesitate to save it from the cost of the wheel bolt. If I disassemble the filament, the wheels will remain inside or the flange will stop to fit out.

When the car is in the trailer, the plug bolts will not turn if the wheel swings already
The original rim does not stay inside, the 16 inch original does not stay inside.
Use whichever way you like

Thank you very much.

Hi my friend. I have a 17 "multi-spoke wheel in my 2001 model 1.6 xs. I want to replace them and get 16". What should be the size ???? Your 16 "is. What is the width of it ???