The ETRTO standards include long lists as well as calculation formulas. Before I describe these formulas for a long time, I created a file that allows a quick calculation. Since only certain file extensions are allowed in the forum, I have packed them into a ZIP archive. The HTML file in it can be opened with a web browser. Greeting Alpha Lyrae Important supplement: The calculation formulas used in the file correspond to those used in the ETRTO Engineering Design Information. This does not necessarily imply the admissibility of a combination of tyre cross-section and rim contour. Secure values for possible rim contours to a tyre q The ETRTO Standards Manual gives only the cut-off. There are some deviations from the formulas of the EDI.