  We investigate the radius distributions (RD) of surfaces obtained with
large-scale simulations of radial clusters that belong to the KPZ universality
class. For all investigated models, the RDs are given by the Tracy-Widom
distribution of the Gaussian unitary ensemble, in agreement with the conjecture
of the KPZ universality class for curved surfaces. The quantitative agreement
was also confirmed by two-point correlation functions asymptotically given by
the covariance of the Airy$_2$ process. Our simulation results fill the last
lacking gap of the conjecture that had been recently verified analytically and
experimentally.
