Abstract: An automatic date-stamping system for vehicles entering a parking area for a relatively long period of time, i.e., for more than one day rather than several hours, so that the accumulated charges of the parking costs at the time of leaving, are easily and reliably determinable. The date is stamped automatically on the side-wall of a tire of the vehicle in invisible ink, so as not to mar the appearance of the vehicle, before the blocking and/or signalling means are operated to permit entry of the vehicle into the parking area. Exposure of the date-imprint to ultra-violet light or other rays to which the printing ink is responsive, renders it visible for reading at the time of leaving the parking area, or before that time, if such is necessary.