Newtire size. / R. Calculate. 225/40 R18 vs 225/45 R18 comparison results: Speedometer difference. Welcome to our handy wheel and tire size calculator! Put your current tire 24545-R18 tires are 0.06 inches (1.6 mm) smaller in diameter than 225/55-R17 tires and the speedometer difference is 0.3%. Inthe tire comparison table above, you can see a detailed calculation of the size difference between 255/45 R18 and 225/55 R18 tire. The calculation results are presented in the form of visual infographics, on which tire with size 255/45 R18 is on top, and tire with size 225/55 R18 below. Both in the table and in the graph, the tires are Inthe tire comparison table above, you can see a detailed calculation of the size difference between 235/65 R18 and 235/50 R18 tire. The calculation results are presented in the form of visual infographics, on which tire with size 235/65 R18 is on top, and tire with size 235/50 R18 below. Both in the table and in the graph, the tires are Compare235/45 R18 vs 225/40 R18. Tire Size and Comparison Calculator calculate tire diameter from code and compare speedometer differences for tire sizes. The first number 235 is the tire width in millimeters. The 2nd number 45 is used to calculate the sidewall height or "aspect ratio", by percentage. Tire1. / R. 225. 45. R 18. Tire 2. / R. 235. 40. R 19. Inch Mill. KPH MPH. Odometer Reading. If you replace 320/60/18 with 235/60/18 for Odometer reading 1000 the actual distance 23565-R18 tires are 1.85 inches (47 mm) larger in diameter than 235/55-R18 tires and the speedometer difference is 6.1%. 225/45/R18 vs. 225/40/R18. Here's the deal The GS-D3s that I originally wanted are out of stock until the end of October so now I'm down to 3 alternatives. So I think I'm now between BF and GY, but I think BF has it with the better pricing.. The only problem with BF is that they only offer 225/40/R18 which is smaller Tire1. / R. 225. 55. R 18. Tire 2. / R. 225. 45. R 18. Inch Mill. KPH MPH. Odometer Reading. If you replace 320/60/18 with 235/60/18 for Odometer reading 1000 the actual distance Inthe tire comparison table above, you can see a detailed calculation of the size difference between 255/40 R18 and 255/45 R18 tire. The calculation results are presented in the form of visual infographics, on which tire with size 255/40 R18 is on top, and tire with size 255/45 R18 below. Both in the table and in the graph, the tires are vOmF9xJ.