Hi Amy,

It certainly is possible, as that generation of Polo was available with 17-inch wheels. If you stick to the 205/40 size, the overall diameter only increases by five millimetres and the error on the speedo is negligible. The error is considerably more with the 205/45 size. 

You'll need to make sure you get the correct offset on the wheels, however, and ensure that they are not sitting proud of the wheelarches when fitted.

We'd also be worried about the extra weight of the wheels and tyres for the suspension. Hopefully it won't cause any issues there. You may find the tyres rubbing the inside of the arches, which is not acceptable, and you will definitely find the car less comfortable to drive.

So, in short, yes, it's possible to do, but there are downsides.