If you search the part number of the wheels, you will find the bore/offset etc. any part which starts with 4G is for the audi a6 c7, i believe.
If it was me wanting 17s, i think i would be looking for some alloys, there are two or three styles, i think, there are audi winter ones, which are the german ones which are 7.5J and then there are uk spec (SE?) wheels which are 8J, but i think your tyres would be ok on them, id do some research first but its not a big increase in width. There are companies who make/sell steel wheels but as to price, might be more cost effective just to get some second hand alloys. your call on that one though 🙂
Below is the size comparison, as Audi recommend them as i am sure you know, they will be within tolerance, even if not, all it does is alter your speedo reading, but if you are aware of this its ok...
Re the widths, it does seem to be received wisdom that thinner with taller tyres is the way to go.