A wire guide includes a solid core mandrel 21 that is initially received in a flat wire coil 31 that has a rest inner diameter that is greater than a uniform diameter of the solid core mandrel. The flat wire of the flat wire coil is in tension between a proximal location 48 and a distal location 47 so that the flat wire coil has a reduced inner diameter that is smaller than its rest inner diameter. The tension in the flat wire is introduced by torquing the mandrel relative to the flat wire coil as part of attaching the coil to the mandrel.
