Thecalculation results are presented in the form of visual infographics, on which tire with size 245/60 R18 is on top, and tire with size 235/60 R18 below. 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. Thefirst number 235 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 235/55 R 18 tire is 60% of 235 = 192. The 3rd number 18 (generally Inthe tire comparison table above, you can see a detailed calculation of the size difference between 235/60 R18 and 255/55 R18 tire. The calculation results are presented in the form of visual infographics, on which tire with size 235/60 R18 is on top, and tire with size 255/55 R18 below. Both in the table and in the graph, the tires are 26535-R18 tires are 0.1 inches (2.5 mm) smaller in diameter than 235/40-R18 tires and the speedometer difference is 0.4%. Thecalculation results are presented in the form of visual infographics, on which tire with size 235/40 R18 is on top, and tire with size 215/45 R18 below. 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. 25555-R18 tires are 0.98 inches (25 mm) smaller in diameter than 235/65-R18 tires and the speedometer difference is 3.3%. Inthe tire comparison table above, you can see a detailed calculation of the size difference between 225/50 R18 and 235/50 R18 tire. The calculation results are presented in the form of visual infographics, on which tire with size 225/50 R18 is on top, and tire with size 235/50 R18 below. Both in the table and in the graph, the tires are Witha diameter of 25.4 inches, 235/40R18 tires provide 0.31 inches more ground clearance versus 25.09 inches for 225/40R18 tires. This added clearance benefits off-road driving by reducing the risk of scrapes or damage from obstacles. However, the slightly larger 235/40R18 diameter causes a lower speedometer reading than 225/40R18 tires. ForGood Year Asymmetric 2, you can go for 235/40/R18. My stock was 225/45/R18 and changed to 235/45/R18. Still ok for the stock 7.5J rims. High speed stability, grip in the wet and aquaplaning is excellent. Comfort is ok. Same as previous tyres. Noise a Compare225/55 R18 vs 235/45 R18. 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. GrPlvf.