22540R18, 225-45R18 tire size comparison with Size calculator. Use our tire calculator to compare tire sizes based on tire diameter, radius, sidewall height, Inthe tire comparison table above, you can see a detailed calculation of the size difference between 255/55 R18 and 245/60 R18 tire. The calculation results are presented in the form of visual infographics, on which tire with size 255/55 R18 is on top, and tire with size 245/60 R18 below. Both in the table and in the graph, the tires are 21545-R18 tires are 0.53 inches (13.5 mm) larger in diameter than 225/40-R18 tires and the speedometer difference is 2.1%. Ihave run both 245/40/17 and 245/35/18 in MPSS. The 245 18 has 1/2 wider tread. Even in the same tire and brand, the width can be different for widths that are supposed to be "the same". I run 245/35/18 on 18x9 wheels. The are a bit heavier feeling than the 225/40 on 18x8 I had. But they feel more confidence inspiring, and look amazing. 2x225 45 r18 95v Dot 4420 ( Herstellungsjahr 2020 ) Restprofil 2x 7,9mm + 2x 245 40 r18 97v Dot 2720 ( Herstellungsjahr 2020 ) Restprofil 2x 7,1mm Waren auf einem 22535-R18 tires are 0.89 inches (22.5 mm) smaller in diameter than 225/40-R18 tires and the speedometer difference is 3.6%. The245/40R18 tire has the following features: the first three digits 245 refer to the width of the tire in millimetres. The second two-digit number 40 refers to the ratio between the height of the sidewall and the width of the tire. R stands for “Radial” and the last two figures 18 indicate the wheel diameter in inches. 25535-R18 tires are 0.06 inches (1.5 mm) smaller in diameter than 225/40-R18 tires and the speedometer difference is 0.3%. niOBJru.