Stans Arch S2 Rear Wheel - 27.5" 12 x 148mm 6-Bolt XDRStans No Tubes Arch S2 Rear Wheel 27. 5" 12 x 148mm 6 Bolt XDR. Arch S2 wheelsets have the versatility to handle a wide range of riding conditions and are the ideal upgrade for Trail AM Enduro and eBikes. When your average ride includes both tough climbs and rough descents and you want the best tubeless system in the business the Arch S2 is for you. Versatile 28mm internal rim width optimized for 2. 2 2. 5 tires 6061 aluminum with sleeved joint and