Single scale tadpoles and O(GFmt2αs3) corrections to the ρ parameter

We present a new set of high precision numerical values of four-loop single-scale vacuum integrals, which we subsequently use to obtain the non-singlet corrections to the ρ   parameter at O(GFmt2αs3). Our result for Δρ is in agreement with the recent calculation [K.G. Chetyrkin, M. Faisst, J.H. Kuhn, P. Maierhofer, C. Sturm, hep-ph/0605201].