The wheels on my '98 UK spec Turbo are starting to look a bit tatty. The outside viewable section, which is stove enamelled, looks fine. But it's the bit you can see if you look through the spokes that worries me. I've always cleaned this section (skinned knuckles every time!!) though now it's becoming discoloured as though oxidation has begun (due to winter weather and salt I guess). This section is'nt enamelled. Am I supposed to let it get dirty to hide the problem? Anyone have the same problem or approached their dealer about it as a warranty job? Any cures?