  We investigate the size scaling of the conductance of surface disordered
graphene sheets of width W and length L. Metallic leads are attached to the
sample ends across its width. At E ~ 0, the conductance scales with the system
size as follows: i) For constant W/L, it remains constant as size is increased,
at a value which depends almost lineally on that ratio; this scaling allows the
definition of a conductivity value that results similar to the experimental
one. ii) For fixed width, the conductance decreases exponentially with length
L, both for ordered and disordered samples. Disorder reduces the exponential
decay, leading to a higher conductance. iii) For constant length, conductance
increases linearly with width W, a result that is exclusively due to the tails
of the states of the metallic wide contact. iv) The average conductance does
not show an appreciable dependence on magnetic field. Away from E = 0, the
conductance shows the behavior expected in two-dimensional systems with surface
disorder, i.e., ballistic transport.
