A friend of mine has a Jetta MK I with Rota RB 8x15 et 24 with 185/45-15 tires, so I just had test how those did fit on my Polo..
Didnt look too bad! Its a tight fit, But drivable... Should have been lower profile..
So I guess 7x15 et 20 with 165/45-15 would go too