AUTOMOTIVE PARTS › AAUSA Radium Engineering Carbon Fiber Fuel Cell Lid - Spare Tire Cell AAUSA Radium Engineering Carbon Fiber Fuel Cell Lid - Spare Tire Cell $343.99 Carbon fiber lid for Radium Spare Tire fuel cells. Constructed with 2x2 3k twill dry carbon fiber. Re-use fasteners that came with fuel cell. Add To Cart Added! Carbon fiber lid for Radium Spare Tire fuel cells. Constructed with 2x2 3k twill dry carbon fiber. Re-use fasteners that came with fuel cell.