If the wheels are washed correctly and not kerbed or damaged they are fine I ran a set of serrons on my mk6 and mk7.5 GTI'ss as winters for the last 7 years still perfect no white worm or corrosion on any.
Bilberry ,wheel cleaner pressure wash off before contact wash and maybe something like autofinnese aqua coat on drying and they will last fine. Corrosion is caused by bad wash technique and wrong wheel cleaning products.
I think luck plays a big part with diamond cut alloys.
Mine were never kerbed, I always used a safe wash technique and safe products, protected them well against the elements and touched in any stone chips as soon as they happened (black paint on the recessed sections and clear lacquer on the diamond cut faces). In spite of this, two of them suffered white worm - and not in areas where stone chips had been repaired.
IMHO a bare metal surface does not provide a good key for the clear lacquer to bond to - especially on the ‘sharp’ edges where the diamond cut face meets the recessed black painted sections - so durability is compromised compared to a powder coated alloy wheel. Also, diamond cut alloys seem to be much more susceptible to damage by tyre fitters than powder coated alloys (tyre fitters didn’t damage mine either, as they were still on the original tyres).
I don’t have any concerns with white worm now - within a few weeks of getting a new car I swap the factory diamond cut alloys for a set of durable powder coated alloys that I can run all year round with no worries of white worm. The diamond cut alloys go back on the car just before I sell it to add a bit of ‘bling’ for the next owner, if that’s their thing, and I sell the powder coated alloys on to recoup some of the cost incurred buying them.
