I've got a mk3 1.4tsi with 225x45x17 wheels and tyres that are starting to show some wear after 33k km and I have a shortlist of the usual Michelin, Goodyear or Continental replacement options depending on what deal in on at the time.

I'm not an aggressive driver and drive to the conditions and I have been tempted by the offer of a very cheap set of steel wheels and very low mileage Continental tyres off a Mk7 Golf.
The thing is the wheel size is 195x65x15 which comes in somewhere close to 2% of the current wheel circumference.
Similar wheel/tyre combinations were fitted to Falcadores not so long ago so it is not really a safety issue and I'm curious as to what effect it will have on the car consumption.

But is it legal, the minimum size fitted was 16 inch, and are there any other factors I have to take into consideration? I assume the bolt holes would be the same although I might need some different bolts?