We investigated the wire orientation dependence of ensemble electron spin dynamics by using a time-resolved Kerr rotation technique in wires made from a modulation-doped GaAs/AlGaAs quantum well. We observed a strong anisotropy of the electron spin dephasing time of as large as 40 depending on the wire orientation at 5 K by tuning the spin-orbit interaction. The wire width dependence of the spin dynamics is reproduced in a Monte Carlo simulation. In addition, two characteristic spin decay rates were observed in wires whose widths were close to the spin precession length. The dependence of the magnetic field direction on the spin dynamics of the wires was also studied to determine the difference from that of two dimensional electron gas.