A security fastener (2, 102) for installation on a wheel (30, 130) having a recess hole (31, 131) extending from a recess entrance (33, 133) of a first diameter, comprising: a threaded end portion (14, 114) concentric with a longitudinal axis (x-x) of said fastener; said threaded end portion configured and arranged to mate with a corresponding threaded element of said recess hole of said wheel when said fastener is installed in said recess hole; an intermediate skirt portion (24, 124) concentric with said longitudinal axis of said fastener and configured and arranged such that a side wall region (18, 118) of said skirt portion will extend within said recess hole when said fastener is installed in said recess hole; said side wall region of said intermediate skirt portion being capable of having a diameter (22,122) within about 6 millimeters of said first diameter of said recess entrance; a drive portion (26, 126) having a tapered outer surface and a plurality of circumferentially spaced longitudinally extending key-receiving grooves (25, 125) in said tapered outer surface arranged in a lock pattern to which a driving torque may be applied; said drive portion configured and arranged such that said lock pattern will be exposed outside, at or inside said entrance to said recess hole when said fastener is installed in said recess hole; characterized in that said tapered outer surface sloping downward and outward away from said longitudinal axis of said fastener from a top surface (15, 115) substantially perpendicular to said longitudinal axis of said fastener to said skirt portion at a taper angle (23, 123) from said longitudinal axis of at least 11 degrees; wherein said tapered outer surface of said drive portion has a Rockwell scale hardness of about HRc 60 or less and said taper angle and said hardness of said tapered outer surface of said drive portion are governed by the function: taper angle ≥ 11.25 + 60 − taper hardness *.75, where "taper hardness" is said Rockwell scale hardness of said drive portion. a threaded end portion (14, 114) concentric with a longitudinal axis (x-x) of said fastener; said threaded end portion configured and arranged to mate with a corresponding threaded element of said recess hole of said wheel when said fastener is installed in said recess hole; an intermediate skirt portion (24, 124) concentric with said longitudinal axis of said fastener and configured and arranged such that a side wall region (18, 118) of said skirt portion will extend within said recess hole when said fastener is installed in said recess hole; said side wall region of said intermediate skirt portion being capable of having a diameter (22,122) within about 6 millimeters of said first diameter of said recess entrance; a drive portion (26, 126) having a tapered outer surface and a plurality of circumferentially spaced longitudinally extending key-receiving grooves (25, 125) in said tapered outer surface arranged in a lock pattern to which a driving torque may be applied; said drive portion configured and arranged such that said lock pattern will be exposed outside, at or inside said entrance to said recess hole when said fastener is installed in said recess hole; characterized in that said tapered outer surface sloping downward and outward away from said longitudinal axis of said fastener from a top surface (15, 115) substantially perpendicular to said longitudinal axis of said fastener to said skirt portion at a taper angle (23, 123) from said longitudinal axis of at least 11 degrees; wherein said tapered outer surface of said drive portion has a Rockwell scale hardness of about HRc 60 or less and said taper angle and said hardness of said tapered outer surface of said drive portion are governed by the function: taper angle ≥ 11.25 + 60 − taper hardness *.75, where "taper hardness" is said Rockwell scale hardness of said drive portion.