Random fatigue limits are experimentally studied on China grade B cast steel wheel. Test data were obtained by employing a so-called small sampling up-and-down test method. Results reveal that fatigue cracks of the present material were commonly initiated from the casting flaw of shrinkage cavities and grew with typical fatigue river-like flowers and striations. To address the scattered test data, randomness of fatigue limits are comparably measured by the existent four approaches, i.e. conventional, Dixon-Mood, Zhang-Kececioglu, and Zhao-Yang approaches. It is verified that Zhao-Yang approach is appropriately applied for the present assessment on random fatigue limits of China grade B cast steel wheel.