The first number 225 is the tire width in millimeters. The 2nd number 50 is used to calculate the sidewall height or "aspect ratio", by percentage. So, the sidewall height of a 225/50 R 16 tire is 60% of 225 = 192. The 3rd number 16 (generally preceded by an "R") is Rim Diameter in inches. This is the diameter of the rims bead seat base, not Tacoma World is not owned by, or affiliated with Toyota Motor Corporation. 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%. 225/55-R17 tires are 1.77 inches (45 mm) larger in diameter than 225/45-R17 tires and the speedometer difference is 6.6%. 235/45-R17 tires are 0.47 inches (11.9 mm) larger in diameter than 225/50-R16 tires and the speedometer difference is 1.9% Latest Tyre Test Results. Positive - Excellent tyre with a balanced performance in all tests, stable in the dry and wet, low noise, low fuel use, good price to performance ratio. Negative - Slightly slow steering response. Overall - Recommended. Positive - A well balanced tyre, good wet handling, high aquaplaning resistance. In the tire comparison table above, you can see a detailed calculation of the size difference between 245/45 R17 and 255/45 R17 tire. The calculation results are presented in the form of visual infographics, on which tire with size 245/45 R17 is on top, and tire with size 255/45 R17 below. Both in the table and in the graph, the tires are Size difference between 215/50 R17 and 205/55 R17 tires. In the tire comparison table above, you can see a detailed calculation of the size difference between 215/50 R17 and 205/55 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 205/55 R17 below. 225/45-R17 tires are 0.11 inches (2.9 mm) larger in diameter than 225/50-R16 tires and the speedometer difference is 0.4%. 205/50-R17 tires are 0.45 inches (11.5 mm) larger in diameter than 215/45-R17 tires and the speedometer difference is 1.8%. 225/45-R17 tires are 0.89 inches (22.5 mm) smaller in diameter than 225/50-R17 tires and the speedometer difference is 3.5%. fpdC4.