This paper presents a time optimization study to find optimal exchanged wheel diameter when internal grinding stainless steel. To do that, the minimum grinding time was elected for the target of the optimization problem. In addition, five process factors were carefully chosen for the exploration. They are the original wheel diameter, the wheel width, the wheel wear per dress, the wheel life, and the total depth of dressing cut. Moreover, to weigh the effects of the input parameters on the optimal exchanged wheel diameter, a simulation experiment was designed and accompanied. In addition, a regression model was presented to estimate the optimal exchanged wheel diameter