A connecting element (10, 100), in particular a bolt or a nut, preferably for fastening a wheel, or rim, to a hub of a vehicle, especially of a motor vehicle such as a motor car, comprises a body (12) having a respective outer perimeter surface (14) which extends along a respective imaginary profile, in particular an imaginary circular profile, there being formed, at the perimeter surface, respective means (16) for the engagement of corresponding means or tool for screwing and/or unscrewing the connecting element, and screw thread means (21) for fastening, preferably to the vehicle hub. The engagement means (16) comprise a plurality of perpendicularly extending and circumferentially distributed engagement troughs (18), these engagement troughs being recessed relative to the imaginary outer profile and each being separated from the adjacent trough (18) by a respective outer perimeter transit zone. The outer transit zone (19) has a width (r) which is less than the width (i) of the trough (18), and in particular, a width (r) which is less than half the width of the trough (18), preferably a width which is less than a seventh of the width of the trough (18).