Just got a new set of metzlers and the sidewalls are very nasty looking. patches of dull or whitish areas interleaved with shiny black, etc. Tried soap and water......better, but still not good. Is there anything i can use on them that will smooth out the apperance? mind you, my last set i used automotive tire products (no need to lecture...won't be doing that again) and i believe they led to the sidewalls developing whether cracking. I asked a while back at rat and 9 out of 10 said thier metzlers aren't cracked at all so it must have been the products i used. i'm in so cal, so the weather isn't harsh either. So i need to clean em up but i wanna be sure i use something that doesn't cause this craking again. Any ideas?