In the tire comparison table above, you can see a detailed calculation of the size difference between 225/50 R17 and 245/40 R18 tire. The calculation results are presented in the form of visual infographics, on which tire with size 225/50 R17 is on top, and tire with size 245/40 R18 below. Both in the table and in the graph, the tires are 245/70-R17 tires are 1.1 inches (28 mm) larger in diameter than 225/70-R17 tires and the speedometer difference is 3.6%. 225/45 R17 235/45 R17: 245/40 R17 225/40 R18 235/40 R18: 225/50 R17: 235/45 R17 245/45 R17: 245/40 R17: Find Us. Contact +27 (0)72 378 0617 +27 (0)43 722 2809. 13a 245/40-17 225/45-17 Difference; Diameter inches (mm) 24.72 (627.8) 24.97 (634.3) 0.26 (6.5) 1%: Width inches (mm) 9.65 (245) 8.86 (225)-0.79 (-20) -8.2%: Circum. inches (mm) 77.65 (1972.29) 78.45 (1992.71) 0.8 (20.42) 1%: Sidewall Height inches (mm) 3.86 (98) 3.99 (101.25) 0.13 (3.25) 3.3%: Revolutions per mile (km) 815.98 (507.02) 807.61 (501. 205/45-R17 tires are 0.81 inches (20.5 mm) larger in diameter than 205/40-R17 tires and the speedometer difference is 3.3%. In the tire comparison table above, you can see a detailed calculation of the size difference between 235/45 R18 and 225/45 R17 tire. The calculation results are presented in the form of visual infographics, on which tire with size 235/45 R18 is on top, and tire with size 225/45 R17 below. Both in the table and in the graph, the tires are 215/45-R17 tires are 1.06 inches (27 mm) smaller in diameter than 245/45-R17 tires and the speedometer difference is 4.1%. Compare 225/55 R16 vs 235/45 R17. Tire Size and Comparison Calculator calculate tire diameter from code and compare speedometer differences for tire sizes. The first number 225 is the tire width in millimeters. The 2nd number 55 is used to calculate the sidewall height or "aspect ratio", by percentage. So, the sidewall height of a 225/55 R 16 245/40-R18 tires are 0.74 inches (18.9 mm) larger in diameter than 225/45-R17 tires and the speedometer difference is 2.9%. In the tire comparison table above, you can see a detailed calculation of the size difference between 215/50 R17 and 235/45 R17 tire. The calculation results are presented in the form of visual infographics, on which tire with size 215/50 R17 is on top, and tire with size 235/45 R17 below. Both in the table and in the graph, the tires are 1j6JziK.