If you think mag rims are hard try wire wheels sometime. Try a very mild abrasive like toothpast. Do a test on a small spot that isn't very conspicuous to see if it helps or hinders. Keep it real wet while rubbing. There are some pro detailers online that probably know a lot of tricks that I dont know. Search around the subject and you will probably find some advice or another forum where you can submit your question again.

 

I also have used paint thinner (mineral spirits) to get nasty stuff off. I used to use terpentine to get road tar off however that was on baked enamel. I never tried it on modern paint. The mineral spirits I've used on modern paint. It never effected the underlying coat in any negative way it just got crud off. Again try a small spot first. Some of the more aggressive solvents will leave you with a sticky mess since they melt plastic, which our paint basically is.

 

Hi Everyone,

This is just to give you an update about my problem. Definitely, those rims have been repainted, even the centercaps. then, as suggested, I've tried the Turtle wax Polishing Compound. that works great and the paint can be removed even if it's hard work. I'm gonna try the mineral spirits during the week end anw will keep you in the loop.
Thanks for all this precious help.