Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
255/65r18 vs 235/70r18 Tire Comparison Side By Side
  255/65-18 235/70-18 Difference
Diameter inches (mm) 31.05 (788.7) 30.95 (786.2) -0.1 (-2.5) -0.3%
Width inches (mm) 10.04 (255) 9.25 (235) -0.79 (-20) -7.8%
Circum. inches (mm) 97.55 (2477.77) 97.24 (2469.92) -0.31 (-7.85) -0.3%
Sidewall Height inches (mm) 6.53 (165.75) 6.48 (164.5) -0.05 (-1.25) -0.8%
Revolutions per mile (km) 649.51 (403.59) 651.58 (404.87) 2.07 (1.28) 0.3%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.94 mph (32.08 km/h)
25 mph (40.23 km/h)24.92 mph (40.11 km/h)
30 mph (48.28 km/h)29.9 mph (48.13 km/h)
35 mph (56.33 km/h)34.89 mph (56.15 km/h)
40 mph (64.37 km/h)39.87 mph (64.17 km/h)
45 mph (72.42 km/h)44.86 mph (72.19 km/h)
50 mph (80.47 km/h)49.84 mph (80.21 km/h)
55 mph (88.51 km/h)54.83 mph (88.23 km/h)
60 mph (96.56 km/h)59.81 mph (96.25 km/h)
65 mph (104.61 km/h)64.79 mph (104.28 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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