###### Abstract
There is existing research in this area that has studied, for example, the extrapolation of load spectrum in the whole lifespan cycle [9] and the minimum sample size of load collection under typical working conditions [10], along with a multi-dimensional damage study of a comprehensive load spectrum [11]. In addition to the in-depth study of load spectrum, it is important to ensure the accuracy of modeling objects as much as possible. The wheel-side electric drive system has a short transmission chain, which eliminates the need for traditional parts such as a differential, half shafts, and a universal joint. Therefore, the gears of a wheel-side electric drive system are critical to output robustness and NVH performance. The study of gear strength has a long history. The [PERSON] formula for calculating bending strength proposed by [PERSON] in 1890 and the [PERSON] formula for calculating contact strength proposed by [PERSON] in 1891 have laid the theoretical foundation for calculating gear bending and contact strength, respectively [12]. On this basis, with the continuous deepening of theoretical research, various methods for calculating the bearing capacity of gears have been proposed. Some countries have established industry standards for gear strength, such as the ISO (International Organization for Standardization) TC 60/SC 2/WG 6 formulas [13]; the DIN (Deutsche Industry Norm) standard 3979-1979 [14]; the AGMA (American Gear Manufacturers Association) standard formulas [15]; the JMS (Japanese Mechanical Society) formulas [16], etc. With the rapid development of computer technology in contemporary times, various commercial gear analysis software programs have emerged [17], such as Masta, Romax, Kisssoft, etc. Due to the high correlation between the tooth root fillet curve and the machining process, commercial software cannot predict and exhaustively list the actual machining status, so it is usually replaced by an approximate equivalent method [18]. However, for gears with high precision and harsh working loads, the fillet is a sensitive factor in FEM (finite element method) analysis, especially in the bending strength of the tooth root [19]. For the wheel-side electric drive system, its gears are processed by hobbing and form grinding, which can modify the gear tooth profile in a free-style way [20]. Form grinding uses a specially refined grinding wheel to meet the customized requirements so that a high quality of tooth precision and surface quality is guaranteed [21; 22]. Therefore, it is necessary to conduct precise tooth profile modeling for the process of hobbing and form grinding, which is decisive for the correctness of simulations and tests. In Section 2, the research object is introduced, including the structure of the wheel-side electric drive system and the modeling of the transmission system. In Section 3, the research method is discussed in detail, including the tooth profile precise calculation, the design parameters of gears, and the load spectrum analysis and equivalent transformation theory for various model working conditions. In Section 4, the prototype development and bench test validation are discussed and presented. Finally, several conclusions are summarized in Section 5.