54
There shouldn't be any problems. As far as I know the SP doesn't lower the car.
In Greece the standard tyres are:
195/65R15 for 316
205/55R16 for 318, 320, 325
225/45R17 for 330
Type 53 is the only alloy in 15".
Type 46 is the standard alloy in 16". I don't like it and it is not popular either. Most people opt for 45, 53 or 54.
My favorite is Type 42 for 225/50R16. It equipped the car I test drived. It was sill to put such a wide tyre on the 316 -it hampered the performace. I went for the standard and rare 15" (instead of the popular 16"), because I don't have to slow too much on the bumps that are all over my neighbourhood ;-) But once a compressor is available for the 4-cyl Valvetronic, I will install it and switch to Type 42.
As I have calculated all of the above give almost the same ride height. But I don't know anyone in Greece that uses winter tyres!