Different compounds and chemicals are added to natural rubber to form tougher bottom soles for some sneakers. Carbon is one compound that is added to rubber to make it longer lasting and much more durable. A carbon and rubber combination makes your sneaker's bottom soles work great while engaging in outdoor sports. This rubber and carbon compound gives better support and traction when enjoying activities on rougher surfaces such as an outdoor concrete basketball court. Carbon and rubber sneaker soles can leave black scuff marks on indoor hardwood floor surfaces however.