There are manufacturing deviations for the overlap distance depending on the manufacturing quality of each part of the door systems. To calculate the manufacturing deviations, the conventional design methods of assembly tolerance allocation typically use the root sum square (RSS) tolerance analysis method (Lin et al., 1997). Despite its limitations, such as one-dimensional calculation and quality control of the 3σ level of Gaussian distribution, it is widely used as a simple and practical analytical tool. When the i-th tolerance of the design parameters (DPs) is set to X_i and N number of associated DPs exist, manufacturing deviation is calculated using Equation (1). The typical tolerances of the DPs are shown in Table 1. The typical δ_ma  is calculated to be 1.87 mm.The upward force of the side door glass due to the stall torque of the window regulator motor deforms the glass and the BIW. This changes the distance between the door inner belt and glass, making it smaller than the designed overlap dimension because the glass is deformed outwardly (Lee and Jeong, 2017; Miklos et al., 2017). This amount of deformation is denoted as δ_st. To measure the δ_st, the distance between the glass and the inner belt was measured using a laser point sensor, as shown in Figure 2. For conservative prediction of the δ_st, aged weatherstrips are prepared and 14.5 V was applied to the regulator rather than the rated voltage of 13.5 V. The measurement results are presented in Table 2. The amount of deformation is large when single rail regulator and laminated glass are used. Even among similar mid-sized vehicles, EVs exhibit large deformation because of the large door width. Despite the similar body size, EVs have a large wheel base to secure interior cabin space, and therefore, the door width is also larger than those of the existing internal combustion engine vehicles.According to ISO 315, the compression set of a material is defined as the permanent deformation retained after the removal of a force that was applied to it. For the inner belt weatherstrip, the initial overlap distance is denoted as ODi, and the overlap distance after aging is denoted as ODa; the compression set ηc is defined as the permanently deformed ratio according to Equation (2). The desired overlap ODdesired is defined as the sum of the stalled deformation (δst) and manufacturing deviation (δma).Because the designed minimum overlap distance must be larger than the desired overlap even after permanent deformation, by substituting Equation (3) into Equation (4), the minimum overlap requirement can be expressed as shown in Equation (5).The smaller the compression set of the elastomer material, the smaller the overlap required, and the smaller the change in the overlap distance, the better the performance maintenance. The ηc of general inner belt weather strip was restricted to within 30%. By substituting δma and δst obtained above into Equation (3) and (4), the ODdesired and ODmin are calculated to be 3.9 mm and 5.6 mm, respectively.