I noticed most sneakers, especially before the 1980s that i’ve seen have gum outsoles. Sometime in the 1970s it seems to have went to rubber colored soles but gum soles were still popular until the 1980s when gum soles seemed to have not been as widely available on sneakers.
What is the difference between gum soles and rubber outer soles?
This right here. Signs on the gym doors said “non marking soles only”. The janitors were pissed and weren’t going to take it anymore. They threatened unionizing but the signs helped calmed them down. They formed a grass roots movement and wrote letters to the manufacturers lobbying for special gym shoes which employed an “eraser” sole. R&D got ahold of it, the rest is bs.