According to the OEM, Dunlop, "No, you should never use protectants, cleaners or dressings on your tire sidewalls. These may degrade rubber and remove the inherent ozone cracking and weather checking resistance put into the rubber by the tire manufacturer.
Use a mild soap solution to clean your sidewalls, white striping or lettering, and rinse off with plain water."
I have used
ProtectAll for years. Works great on just about the entire bike. Great for the seat and sidewalls without making them slippery. I've seen guys at shows use it on the entire bike, including tire tread.