Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
115/85r18 vs 125/70r18 Tire Comparison Side By Side
  115/85-18 125/70-18 Difference
Diameter inches (mm) 25.7 (652.7) 24.89 (632.2) -0.81 (-20.5) -3.1%
Width inches (mm) 4.53 (115) 4.92 (125) 0.39 (10) 8.7%
Circum. inches (mm) 80.73 (2050.52) 78.19 (1986.11) -2.54 (-64.4) -3.1%
Sidewall Height inches (mm) 3.85 (97.75) 3.44 (87.5) -0.4 (-10.25) -10.5%
Revolutions per mile (km) 784.85 (487.68) 810.3 (503.49) 25.45 (15.81) 3.2%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.37 mph (31.18 km/h)
25 mph (40.23 km/h)24.21 mph (38.97 km/h)
30 mph (48.28 km/h)29.06 mph (46.76 km/h)
35 mph (56.33 km/h)33.9 mph (54.56 km/h)
40 mph (64.37 km/h)38.74 mph (62.35 km/h)
45 mph (72.42 km/h)43.59 mph (70.15 km/h)
50 mph (80.47 km/h)48.43 mph (77.94 km/h)
55 mph (88.51 km/h)53.27 mph (85.73 km/h)
60 mph (96.56 km/h)58.12 mph (93.53 km/h)
65 mph (104.61 km/h)62.96 mph (101.32 km/h)
70 mph (112.65 km/h)67.8 mph (109.12 km/h)
75 mph (120.7 km/h)72.64 mph (116.91 km/h)
80 mph (128.75 km/h)77.49 mph (124.7 km/h)
85 mph (136.79 km/h)82.33 mph (132.5 km/h)
90 mph (144.84 km/h)87.17 mph (140.29 km/h)
95 mph (152.89 km/h)92.02 mph (148.09 km/h)
100 mph (160.93 km/h)96.86 mph (155.88 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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