From what I've read about mk3 wheel fitments, ideal tyre sizes to retain your correct rolling radius would be 205/40/16 or 205/45/16.
Standard 15" rims on a mk3 are generally fitted with 205/50/15 or 195/50/15 tyres (205/50/15 on my car), and you want to increase your rim size to 16", so you should really go for a lower profile tyre to compensate or your speedo will be out

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Are the rims off a mk4 by any chance? The rim/tyre size you state is common on mk4s, this information coming from ebay trawling experience, where there is an abundance of mk4 rims for sale

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205/55/16s sound a bit on the large side for a mk3

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All said and done, if you really aren't sure ask your local tyre/exhaust centre for advice or contact your local VW dealer.
There are people on this forum that can tell you for certain which (205/45/16 or 205/40/16) is the best bet, so best wait for another couple of replies before you make up your mind.
Hope this helps

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Phil