Recycled rubber typically comes from end-of-life tires, manufacturing scrap, or post-industrial rubber waste that is ground and reformulated. Sourcing is global, tied to automotive and industrial waste streams. Challenges include unknown original composition (natural vs synthetic blends), additive chemistry, and limited consumer-facing certification. Some suppliers use GRS when rubber is part of a certified recycled supply chain, though it’s less common than in textiles. Recycled rubber is widely used in footwear soles, mats, grips, and durable home goods.