It shall be unlawful for any person to park or leave standing any vehicle at any time in any part of the city, except with the right hand side thereof parallel with the curb and not more than one foot from the curb; provided, that the traffic division may designate any street or portion thereof where vehicles shall be parked at an angle, and all vehicles when parked on any such street or portion thereof shall be parked at the designated angle, with the right front wheel of such vehicle at the curb. Where the stalls are designated either on the curb or on the pavement, vehicles will be parked within such stalls. It shall be unlawful for any person to park or leave standing any vehicle beside any vehicle which is lawfully parked parallel with the curb of a street or behind any vehicle which is lawfully parked at an angle to the curb of a street, nor shall any vehicle be parked beside any vehicle on the main traveled portion of the street.