Oh no, you've dun it now, got me going on a favourite hobby horse - warning miserable git man on soap box!
The Polo used to be a small car, but decades back German cars like VWs got very overweight very soon so that was one factor to wheel size. But the main factors are fashion, wheels have got bigger as part of willy-waving, mine's-bigger-than-yours (penis substitutes for non-male owners) then to be Gangster and "to fill the wheel arches", they must be filled!
Depending on the brakes 14" wheels would easily be enough even allowing for VW's excess weight on all models but how could you possible let people see such a diminutive part, the shame.
I took a guess at 2005 for the year of the car and if the website is correct it shows 205/45R16 83V - 6.5J x 16, ET43. Some of the engine power is need to push these four tractor wheels and tyres against the road surface and they throw off more 'rubber' bits and give their wider hum road noise. They must be for semi-amphibious use, happily riding on water.
For 14" 185/65R14 was the nearest I could get for tyre size, 14" wheels show as 6J1x14, ET43. The 185 are a little taller (within 3% for speedo) and give nominal 112mm sidewall against nominal 91mm for 16" tyre, a bit more 'rubber' cushioning on the potholes and smaller hopefully sturdier 14" wheel.
run4mo (and I) will remember when 185/70 was the low profile for tyres, back in the last millennium, but somehow these skinny balloon tyres kept the fast cars on the road ,we were driving heroes, all muscle from the lack of power steering (other than the pedal under the right foot) .
Admittedly the 16" V rated tyres are good for 149mph if the poor old engine has any puff left from hauling the car, the tyre width doesn't seem necessary for power or torque output but good to have plenty of spare margin perhaps.
Ahhhhhh,I feel better for that. Someone put up a photo of an original Mk1 Polo parked next to a Mk4 ,see what a bully it turned into. 😁
ETA: You've only spent £4k in seven years(?) I thought you meant months, cumm'n yer not trying now. 😄