Had a bit of a scary afternoon, yesterday. Wiped the wheels over with some water-based panel wipe, prior to putting on some nice wax. Never had a problem with this stuff before.
The wheels went mostly white!! Had to spend about 45 minutes per wheel with cutting polishes to get this stuff off - not nice in the heat! Still a few spots (looks like water-marks) remaining now.
I suspect the lacquer may be on the way out; the wheels have been looking far from shiny in the wet recently and this is most odd.
Just a warning to others: looks like the lacquer's pretty damned soft on the wheels (or is certainly so after 8 years).
Would have taken pictures, but really didn't want to stop the recovery process.
Will probably get the wheels refurbished soon.