I dunno if anyone will chime in with a definitive answer. When I was asking this question I used a tire size calculator and my current tire size. Then with the new tire dimensions, I started looking at possible rub spots. For my 96 Passat, it seemed to me the first place of contact would be the spring perch on the strut. I made a best guess and was pretty close. I could maybe go one series larger.
Check out the tire size calculator here:
https://www.1010tires.com/Tools/Tire-Size-Calculator
This has been discussed some in the past. So there is some info out there. Without wheel spacers or a lift, I bet you could run 195/75 R14. 185/75 R14 would probably be an easy fit. But then again, I'm a Passat owner so my opinion doesn't mean much on the A3.
I run 195/75 R14 on my 96 Passat. I have a lift, but probably wouldn't need it to run these tires.
Odie is running 205/75 R14 on his Passat with a smaller lift and only some slight body rubs on speed bumps over 20mph. I would probably like to try this tire size next since I have a larger lift then Odie.