Thefirst number 215 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 215/55 R 17 tire is 60% of 215 = 192. The 3rd number 17 (generally
Inthe tire comparison table above, you can see a detailed calculation of the size difference between 205/55 R16 and 225/45 R18 tire. The calculation results are presented in the form of visual infographics, on which tire with size 205/55 R16 is on top, and tire with size 225/45 R18 below. Both in the table and in the graph, the tires are
20555-R16 tires are 2.13 inches (54 mm) smaller in diameter than 215/65-R16 tires and the speedometer difference is 7.8%.
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