Method of coating an expandable member includes providing an expandable member having a proximal and a distal end with a guidewire lumen extending therebetween, the expandable member having a deflated and fully expanded configurations, and inflating the expandable member to an initial inflation pressure; positioning a mandrel within the guidewire lumen; tensioning the mandrel to straighten the guidewire lumen within the expandable member; and disposing a therapeutic agent on at least a portion of the expandable member. Method further includes partially deflating the expandable member to an intermediate pressure, and drying the therapeutic agent on the expandable member, and, if a folded expandable member is used, at least partially refolding the expandable member.