The original white color is deep into the tire, so if it was worn away you would be able to tell because it would be gouged out. What little improvements I got with today's "cleaners" was very temporary, and the white soon turned back to brownish. And speaking of today's cleaners, many of them are worthless because they've been de-fanged by environmental concerns. Good traditional cleaners like 409, Fantastic, and others are not even effective in the kitchen anymore!
If it's safe for the environment, it's lousy as a cleaner. They can pull the wool over Millennial's, but not us Boomers!
Rant over.