What carbon rubber is
Carbon black is a fine powder of almost pure carbon, made by burning oil or gas under controlled conditions. In rubber it is a reinforcing filler: its particles bond physically to the rubber chains and stiffen the network. More carbon black means higher tensile strength, tear resistance and abrasion resistance, along with higher hardness. "Carbon rubber" is a footwear term for compounds where this loading is pushed high to maximise wear life.
How carbon rubber outsoles are made
The process is the same as for other solid rubber outsoles: compounding in an internal mixer, sheeting, cutting blanks and vulcanizing them in a heated compression mold. The difference is in the recipe. Carbon black content is increased and often combined with butadiene rubber, which further improves wear resistance. Because carbon black colors the compound black, carbon rubber is almost always black or very dark.
Grip: 4 / 8, Medium
Higher hardness means the compound conforms less to the surface, so carbon rubber grips less than softer compounds, especially on wet, smooth floors and on cold surfaces. Tread design can recover some of that grip, but on surfaces where slip is a risk, carbon rubber is usually best kept to the heel and paired with a softer forefoot compound.
Flex: 4 / 8, Medium
The stiffer network that makes carbon rubber durable also makes it resist bending. A fulllength carbon rubber outsole can make a shoe feel stiff through toe-off. Thinner sections, flex grooves and zoned placement keep the forefoot flexible.
Abrasion: 8 / 8, Max
Carbon rubber is among the most wear-resistant outsole compounds, with low volume loss when tested to ISO 4649. That makes it the standard choice for the heel strike zone of running shoes and the outsole of high-mileage trainers. The more wear resistance you specify, the more grip and flex you give up, so the loading should match how the shoe will be used.
Where carbon rubber is used
- Running shoe heels — the high-wear landing zone of road running and walking shoes.
- High-mileage trainers — full-coverage outsoles where longevity matters most.
- Work and outdoor footwear — heel and edge reinforcements that take abrasion and scuffing.
- Outdoor hard surfaces — asphalt, concrete and gravel, where wear is high and floor marking is not a concern.
Designing with carbon rubber
Use carbon rubber where wear is the main problem and grip is less critical. Combine it with softer compounds where the foot needs traction or flexibility.
- Place it in the heel and outer edges; use blown or softer solid rubber in the forefoot.
- Avoid it for indoor courts and floors where black marking is not acceptable.
- Keep sections thin and grooved to limit stiffness.
- Test wet grip, not only abrasion, before signing off a carbon rubber outsole.