The realization of conducting nanostructures at the interface between LaAlO3 and SrTiO3 is an important step towards the realization of devices and the investigation of exotic physical regimes. We present here a detailed study of the conducting nanowires realized using the atomic force microscopy writing technique. By comparing experiments with numerical simulations, we show that these wires reproduce the ideal case of nanoconducting channels defined in an insulating background very well and that the tip bias is a powerful knob to modulate the size of these structures. We also discuss the role of the air humidity that is found to be a crucial parameter to set the size of the tip-sample effective interaction area.