Everydays a school day!!
I thort white worm was caused by damage of the wheel...thank you for enlightening me
I should have said more clearly...it IS caused by damage to the wheel!
Usually minute damage of small stones hitting the wheel as you drive. Grit, heavy dist at speed etc impacts the wheel and makes a minute impact mark on the lacquer...over time moisture gets in...and bingo! Whiteworm.
Sometimes it's an uneven lacquer coating leaving exposed metal (or even chrome type finished plastic) but normally it's from very small impact marks.
Driving through winter on gritted/salty roads will inevitably lead to the dreaded whiteworm...and sadly, although loads of sealant/wax helps, it won't stop it.