CST Chicopee Pro Tire 26 x 2.1 Black Aramid Bead CST Chicopee Pro Tire 26 x 2.1 Black Aramid Bead Pro tires have 60 tpi casing and a lightweight puncture resistant layer between the tread and casing ISO Diameter: 559 ISO Width: 53 mm PSI: 35 -65 PSI 60 tpi casing