Knex 3" Large Wheels Lot of 5 Gray Hub Black Rubber Tread Replacement Parts STEM K'nex replacement wheels lot of five features a rugged tread design perfect for custom vehicle builds or restoring classic sets. These large black tires with gray hubs are compatible with standard K'nex rods and connectors, offering a durable construction for mechanical projects. Ideal for hobbyists looking to expand their building part inventory with high-traction components. Measurements: • Diameter: 3"