To read the measurements of a tube, you usually need to look for three numbers written on the outer surface of the tube. These numbers indicate the diameter and width of the tube, as well as the tire size that the tube is designed for. Measurements are usually written in inches or millimeters. Example of how to read the measurements of an inner tube: Let's say you have an inner tube with the numbers "700 x 25/32c" written on it. This indicates that the inner tube is designed to fit a tire with a diameter of 700mm and a width of 25mm to 32mm. The "c" at the end indicates that the tire is a clincher type. If the measurements were in inches, it would be written as "27 x 1-1/8 to 1-1/4". This would indicate that the tube is designed to fit a tire with a diameter of 27 inches and a range of widths from 1-1/8 inches to 1-1/4 inches. It is important to ensure that the tube you choose is compatible with the size and width of the tire to ensure proper fit and function.