Factory approved fitments:

Mk6 Golf

GTI, GTI Edition 35
225/35 R19 88Y XL

R
235/35 R19 91Y XL


Mk7 Golf

GTI, GTI PP, GTD
225/35 R19 88Y XL

R
235/35 R19 91Y XL

...

As determined by the European Tyre and Rim Technical Organisation (E.T.R.T.O.):

Tyre size 225/35 R19 have approved rim widths of 7.5J, 8.0J, 8.5J & 9.0J, and

Tyre size 235/35 R19 have approved rim widths of 8.0J, 8.5J, 9.0J & 9.5J.


Vehicle manufacturers are not obliged to adhere to E.T.R.T.O. standards, but most do.

...

With regards to DrK's vehicle, allow me to add fuel to the speculation:

How certain are we that the current tyres on his vehicle were fitted at the factory?

I would actually find it more plausible and be less surprised if there was a batch of wheels fitted with the incorrect tyre on the factory floor.

...

With regards to Ben's vehicle, OE wheels are strong, but not indestructible. Failures, though uncommon, are not unheard of.

Also, this is the internet, so keep in mind there are always three sides to any story: yours, mine and the truth.