a mud flap body having a front face and a rear face;

a screw-threaded attachment bolt received into a through-hole formed in the mud flap body from the front face to the rear face thereof, the bolt disposed on an axis;

a rotating clamping member having a center hole which is threadably carried on the attachment bolt, the rotating clamping member disposed rearwardly from the rear face of the mud flap body, a clamping arm of the rotating clamping member extending radially outwardly from the bolt axis and terminating in a clamping end, a stop arm of the rotating clamping member extending radially outwardly from said axis to be angularly displaced from the clamping arm, the stop arm terminating in a stop end, the rotating clamping member rotatable around the axis from a disengaged position to a second position;

a stop formed to extend rearwardly from the rear side of the mud flap body, a height of the stop measured in an axial direction preselected to intersect an arc of travel of the stop end of the rotating clamping arm such that the stop end of the clamping arm will abut the stop when the rotating clamping member reaches the second position; and

an edge of the mud flap body placed forwardly of the fender fold, the rotating clamping member and the attachment bolt rotatable as a unit from the disengaged position to the second position such that the clamping end of the rotating member becomes positioned to the rear of the fender fold, and such that the stop end of the rotating member abuts said stop, further rotation of the attachment bolt causing the rotating clamping member to be drawn axially forwardly toward the rear side of the mud flap body and causing the clamping of the fender fold between the clamping end of the rotating clamping member and the edge of the mud flap body.