Speedlines - a bit soft!

[rick.e]

My Griff is fitted with 17 inch Speedlines all-round. A couple of months back I had new tyres fitted and unfortunately due to a nail, have just replaced one of the fronts again, despite only have 600 miles on the one I took off. The 235/40x17 front tyres have b*****r-all strength in the sidewalls and are very difficult to change and it is apparent that the plating chips off the wheels easily during tyre changes, revealing a creamy white under-surface. One wheel has also lost some plating round one of the nuts, presumably from a badly supported wheel-brace.

Anyone else found this problem? What is the best way to "touch-up" the damage?