Gum is the name of the compound. It is much softer and tackier than the average compound used for tires/grips. In sense, it should wear faster because of this, but alot of people have told me their gum grips last longer than their black versions of the same grips, so idunno. My friends gum tires attract dirt/dust like no other. I would suggest against them if you ride anywhere slick or dusty, theyre the way to go otherwise.
My only personal experience with gum is the gum soles on my shoes. Theyre much more grippy than black soled versions of the same shoes, but they also get torn apart much easier.
Refs : SnM An1mal, GThompson121, Chuck8273, blizzbikes, bmxsteve99, kevin.brock.338, zinum, Brian_Griffin, billyhandyjunior, riverM, tomdon
Instagram : @timhankinsbmx