C-type asteroid
The largest unequivocally C-type asteroid is 10 Hygiea, although the SMASS classification places the largest asteroid, 1 Ceres, here as well, because that scheme lacks a G-type.
(285263) 1998 QE2
With a diameter between 2.7 and 3.2 kilometers, is one of largest known potentially hazardous asteroid "(see PHA-list)". Conversely, the "Collaborative Asteroid Lightcurve Link" assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 1.08 kilometers based on an absolute magnitude of 17.2.