Stans Arch MK4 Rear Wheel - 27.5 12 x 148mm 6-Bolt HG11 MTN BlackStans NoTubes Arch MK4 Rear Wheel 27. 5 12 x 148mm 6 Bolt HG11 MTN Black. The Arch MK4 wheelset is an ideal choice for All mountain Downcountry and Trailduro a versatile aluminum wheelset available for riders who want to push the limits on every trail. Up down and wherever the ride takes you the Arch MK4 wheelset has it under control. Versatile 28mm internal rim width optimized for 2. 2 2. 5 tires Light and durable 6069 aluminum with welded joint and