We have constructed an ε-finite basis of master integrals for all
new types of one-scale tadpoles which appear in the calculation of the
four-loop QCD corrections to the electroweak ρ-parameter. Using
transformation rules from the ε-finite basis to the standard
minimal-number-of-lines basis, we obtain as a by-product analytical
expressions for few leading terms of the ε-expansion of all
members of the standard basis. The new master integrals have been
computed with the help of the Pade method and by use of difference
equations independently.