The first number 205 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 205/55 R 16 tire is 60% of 205 = 192. The 3rd number 16 (generally preceded by an "R") is Rim Diameter in inches. Simple and powerful tire width, height, and diameter calculator. Compare wheel size and speedometer difference. 215/65 R16 vs 225/60 R16; 215/70 R15 vs 205/75 R15 The first number 225 is the tire width in millimeters. The 2nd number 45 is used to calculate the sidewall height or "aspect ratio", by percentage. So, the sidewall height of a 225/45 R 17 tire is 60% of 225 = 192. The 3rd number 17 (generally preceded by an "R") is Rim Diameter in inches. 205/55-R16 tires are 0.21 inches (5.3 mm) smaller in diameter than 225/40-R18 tires and the speedometer difference is 0.9%. 205/55-R16 tires are 1.09 inches (27.8 mm) smaller in diameter than 225/45-R18 tires and the speedometer difference is 4.2%. 225/50-R17 tires are 0.37 inches (9.3 mm) larger in diameter than 205/65-R15 tires and the speedometer difference is 1.4%. So, the sidewall height of the 245 tires would be 245 x 0.45 = 110.25 millimeters, and the 225 tires would have a sidewall height of 225 x 0.45 = 101.25 millimeters. The difference between the two is 9 millimeters (110.25 – 101.25). However, since there are two sidewalls (one on top and one on the bottom), the total height difference between 225/55-R16 tires are 0.87 inches (22 mm) larger in diameter than 205/55-R16 tires and the speedometer difference is 3.4%. wy0GP.

difference between 205 and 225 tires