A wheel-activated vehicle restraint for use at a loading dock includes a wheel-blocking barrier that is selectively locked to a frame by a latching mechanism that engages an inverted gear rack. Components of the latching mechanism are arranged to prevent spreading apart upper and lower members of the frame members. The latching mechanism includes an alignment device that helps ensure that the teeth of a latching member positively engages the teeth of the gear rack, thus preventing the teeth from coming together peak-to-peak. An upper rail of the wheel restraint's frame includes a contoured leading edge that smoothly guides the lift of the wheel-blocking barrier from its stored position to its wheel-chocking position. A wheel support is used to prevent a vehicle's mud flap from getting pinched between the vehicle's wheel and a trigger assembly of the wheel restraint.