205/55-R16 tires are 1.09 inches (27.8 mm) smaller in diameter than 225/45-R18 tires and the speedometer difference is 4.2%.
205/55-R16 tires are 0.1 inches (2.6 mm) smaller in diameter than 195/65-R15 tires and the speedometer difference is 0.4%. These tires range in width from 8.4 inches to 8.9 inches and could have a diameter between 28.1 and 28.4 inches. They fit on 15 inch by 6 inch rims so new rims would be required. You will need to measure the trailer to determine if the wider and taller 225/75-15 tire will fit. The new size will be 1-1/4 inches wider (max) and 1 inch taller (max). Both in the table and in the graph, the tires are compared according to the following indicators: overall diameter, section width, circumference, sidewall height and clearance. Also, the online application calculates the difference in real speed and speedometer readings if the difference between tire 205/75 R14 and tire 225/75 R14 is significant. F9YT.