Originally Posted by WhyFi

I've recently begun to wonder if disc brakes are at least partially responsible for the increased interest in tan/gumwalls.

With shiny brake tracks, gumwalls can look kind of busy with all of those concentric circles/colors, and don't really dig the look. Conversely, with discs bikes that don't have a gleaming brake track, black tires on black rims can look kind of boring and monolithic, so I think that the gumwalls adds a little visual interest.