Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
325/40r18 vs 255/50r17 Tire Comparison Side By Side
  325/40-18 255/50-17 Difference
Diameter inches (mm) 28.24 (717.2) 27.04 (686.8) -1.2 (-30.4) -4.2%
Width inches (mm) 12.8 (325) 10.04 (255) -2.76 (-70) -21.5%
Circum. inches (mm) 88.71 (2253.15) 84.95 (2157.65) -3.76 (-95.5) -4.2%
Sidewall Height inches (mm) 5.12 (130) 5.02 (127.5) -0.1 (-2.5) -1.9%
Revolutions per mile (km) 714.26 (443.82) 745.88 (463.47) 31.62 (19.65) 4.4%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.15 mph (30.82 km/h)
25 mph (40.23 km/h)23.94 mph (38.53 km/h)
30 mph (48.28 km/h)28.73 mph (46.23 km/h)
35 mph (56.33 km/h)33.52 mph (53.94 km/h)
40 mph (64.37 km/h)38.3 mph (61.65 km/h)
45 mph (72.42 km/h)43.09 mph (69.35 km/h)
50 mph (80.47 km/h)47.88 mph (77.06 km/h)
55 mph (88.51 km/h)52.67 mph (84.76 km/h)
60 mph (96.56 km/h)57.46 mph (92.47 km/h)
65 mph (104.61 km/h)62.24 mph (100.17 km/h)
70 mph (112.65 km/h)67.03 mph (107.88 km/h)
75 mph (120.7 km/h)71.82 mph (115.58 km/h)
80 mph (128.75 km/h)76.61 mph (123.29 km/h)
85 mph (136.79 km/h)81.4 mph (131 km/h)
90 mph (144.84 km/h)86.19 mph (138.7 km/h)
95 mph (152.89 km/h)90.97 mph (146.41 km/h)
100 mph (160.93 km/h)95.76 mph (154.11 km/h)

Gear Ratio / RPMs for New Tire (@ 65 mph)
2.35 2.73 2.94 3.07 3.21 3.31 3.42 3.55 3.73 3.91 4.11 4.27 4.56 4.88 5.13 5.29 5.38 5.71 6.17 7.17
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