Sorry, I don't have any suggestions that you haven't tried already but I wouldn't recommend any harsh chemicals like brake cleaner.
Just thought of one. Maybe rubbing compound used for taking off oxidation from your paint. Try one that's the last step before wax, very fine. It certainly won't hurt it. Finish off with wax to help seal it. I use one all the time for boot scuffs, exhaust stains etc. and it works great.
Please let us know and good luck!
Just thought I'd post an update on this problem.....I tried allsorts to clean the wheel up, then last weekend tried your idea Denzee. But unfortunately the outcome was the same as what the lads said on the 'Repsol' forum, when I popped in to pick their brains.
The wheel just goes straight to a matt finish!!! The finish layer, colour layer and primer layer have got to be the finest and most thinly coated paints of all time
Just a slight rubbing takes out the crap on top of the finish coat
, BUT also the nice shiny finish, then TOO MUCH pressure and you're into the WHITE primer before you know it
The lads in the 'Repsol' forum had found out that it seemed to be a major wheel paint problem that Honda wasnt that interested in
So I now need to get a finnishing coat put on the wheel to bring the colour back from matt.
There is one plus to this...I have a nice clean wheel now
But then again I was probably the only person that would have noticed it in the 1st place, as you do!!!