Commuting to work or school on black ice just got faster and easier with the Xerxes. 140 studs provide unrivaled control on those morning rides where ice patches threaten your commute. When a layer of snow conceals black ice, the ultra-narrow profile easily slices through the fluff and gets straight to business providing extreme traction in these extreme conditions. Run the Xerxes at minimum pressure for traction performance, and maximum pressure for a quieter and faster ride on clean roads. - 140 Steel Carbide Studs - Fast-rolling center tread - Narrow profile to fit in most 700c frames - We design 45NRTH tires for extreme winter cycling applications. We do not recommend this product be used with power assist bikes as the additional torque and system weight can lead to pre-mature casing wear and stud loss.