The availability of spare parts for automotive products is one part of after-sales service, which is a critical factor that must also be considered to support customer acceptance and maintain the sustainability of the sales of these products. The fluctuating characteristics of demand for spare parts is a challenge for automotive manufacturers in preparing inventory levels so that they are always available in the correct quantity and time when customers need them. This study adds the objective function of profit and constraint of fill rate and costs in the calculation of the optimization model and is applicable for probabilistic demand characteristics. In addition, inventory classification based on the results of profit and fill rate optimization can be utilized as a reference for companies to prioritize and review the inventory management of existing SKUs.