Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
235/55r20 vs 235/65r18 Tire Comparison Side By Side
  235/55-20 235/65-18 Difference
Diameter inches (mm) 30.18 (766.5) 30.03 (762.7) -0.15 (-3.8) -0.5%
Width inches (mm) 9.25 (235) 9.25 (235) 0 (0) 0%
Circum. inches (mm) 94.8 (2408.03) 94.33 (2396.09) -0.47 (-11.94) -0.5%
Sidewall Height inches (mm) 5.09 (129.25) 6.01 (152.75) 0.93 (23.5) 18.2%
Revolutions per mile (km) 668.32 (415.28) 671.65 (417.35) 3.33 (2.07) 0.5%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.9 mph (32.03 km/h)
25 mph (40.23 km/h)24.88 mph (40.03 km/h)
30 mph (48.28 km/h)29.85 mph (48.04 km/h)
35 mph (56.33 km/h)34.83 mph (56.05 km/h)
40 mph (64.37 km/h)39.8 mph (64.05 km/h)
45 mph (72.42 km/h)44.78 mph (72.06 km/h)
50 mph (80.47 km/h)49.75 mph (80.07 km/h)
55 mph (88.51 km/h)54.73 mph (88.08 km/h)
60 mph (96.56 km/h)59.7 mph (96.08 km/h)
65 mph (104.61 km/h)64.68 mph (104.09 km/h)
70 mph (112.65 km/h)69.65 mph (112.1 km/h)
75 mph (120.7 km/h)74.63 mph (120.1 km/h)
80 mph (128.75 km/h)79.6 mph (128.11 km/h)
85 mph (136.79 km/h)84.58 mph (136.12 km/h)
90 mph (144.84 km/h)89.55 mph (144.12 km/h)
95 mph (152.89 km/h)94.53 mph (152.13 km/h)
100 mph (160.93 km/h)99.5 mph (160.14 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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