Marty, here on the east coast we have a product called Lestoil. You may not have it. It is an old household cleaning product, I find it in REAL hardware stores or old grocery stores. It works the best for me on all rubber products, including white walls. I also use it to soften rubber grommets or pedal pads that can't be replaced. I soaked it into a pair of old stiff floormats several years ago and they've stayed plyable. The whitewall cleaner that Coker sells work very good too.
