Tom the "Roadmaster"

While I am a retired engineer now, I am reminded of a group of Packard Engineers whose car club from the early 1970's, firmly believed the yellowing was from oxidation of the rubber surface. In retrospect I believe this was reasonably correct as those cars were in storage most of the time and never saw a rainy or snowy day, let alone a dirty road (meaning dirt road)! The surefire method I witnessed for removing it was the use of 400 wet sandpaper; used with generous amounts of water to prevent heat burns. I personally liked to start with 200 wet sandpaper and finish with 400 to keep a smooth surface. The use of a pure silicone (or other non yellowing "rubber safe") dressing is very helpful, particularly when in storage, to keep oxygen from interacting with the rubber. Don't laugh, but the use of "Cling Wrap" for food storage suggest long ago by my mother tightly fitted to the white wall surface, while the tires are in storage, showed significantly less yellowing then tires left unprotected. Hope this helps. Tom