245/40-R17 tires are 0.61 inches (15.5 mm) smaller in diameter than 235/45-R17 tires and the speedometer difference is 2.4%. 225/55-R16 tires are 0.77 inches (19.6 mm) larger in diameter than 225/45-R17 tires and the speedometer difference is 3.0%. Aug 28, 2020 · I just picked up 2013 wrx wheels 17x8 +53. I was considering using 235/45r17 or 245/45r17 with 15mm spacers all around. Don’t mind the Speedo being off by a little. I mainly drive on streets in California occasionally will hit icy roads when I drive to utah, mammoth or big bear. I am also planning on using rokblokz short mudflaps. 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 235/45 R17 and tire 235/50 R17 is significant. 245/45-R17 tires are 0.06 inches (1.6 mm) smaller in diameter than 225/55-R16 tires and the speedometer difference is 0.3%. 245/45-R17 tires are 0.65 inches (16.4 mm) smaller in diameter than 235/45-R18 tires and the speedometer difference is 2.5%. In the tire comparison table above, you can see a detailed calculation of the size difference between 245/45 R17 and 245/40 R17 tire. The calculation results are presented in the form of visual infographics, on which tire with size 245/45 R17 is on top, and tire with size 245/40 R17 below. Both in the table and in the graph, the tires are 255/45-R17 tires are 0.35 inches (9 mm) larger in diameter than 245/45-R17 tires and the speedometer difference is 1.4%. 245/45-R17 tires are 0.63 inches (16 mm) smaller in diameter than 215/55-R17 tires and the speedometer difference is 2.4%. 245/40-R18 tires are 0.39 inches (9.9 mm) larger in diameter than 235/45-R17 tires and the speedometer difference is 1.5%. 3LqgcW.