Subsurface internal cracking is one of the most frequent damage mechanisms in railway wheels. In this paper, a hybrid approach is proposed to determine the stress intensity factor of internally cracked bodies, mainly devoted to the analysis of railway wheels but easily adaptable to other practical cases. It is based on the application of the Hertz analytical displacement field to a finite element model of the cracked zone of the wheel. After the description of the method, results are shown referring to cases of practical interest. The comparison with the values experimentally obtained by means of an appropriate photoelastic technique is discussed critically.