Extremely air-tight! Less air loss means having to inflate less. A unique rubber mixture makes it possible. Extremely reliable! Each SCHWALBE tube is individually examined twice at the factory to ensue air-tightness. Special quality control that prevents unpleasant surprises. Â Â 40-559---------26 x 1.50Â Â Â 47-559---------26 x 1.75 50-559---------26 x 2.00Â 54-559---------26 x 2.10 57-559---------26 x 2.25Â 60-559---------26 x 2.35Â Â Â 62-559---------26 x 2.50Â Â Â