Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
145/70r18 vs 145/90r18 Tire Comparison Side By Side
  145/70-18 145/90-18 Difference
Diameter inches (mm) 25.99 (660.2) 28.28 (718.2) 2.28 (58) 8.8%
Width inches (mm) 5.71 (145) 5.71 (145) 0 (0) 0%
Circum. inches (mm) 81.66 (2074.08) 88.83 (2256.29) 7.17 (182.21) 8.8%
Sidewall Height inches (mm) 4 (101.5) 5.14 (130.5) 1.14 (29) 28.6%
Revolutions per mile (km) 775.93 (482.14) 713.27 (443.2) -62.66 (-38.94) -8.1%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)21.76 mph (35.01 km/h)
25 mph (40.23 km/h)27.2 mph (43.77 km/h)
30 mph (48.28 km/h)32.64 mph (52.52 km/h)
35 mph (56.33 km/h)38.07 mph (61.28 km/h)
40 mph (64.37 km/h)43.51 mph (70.03 km/h)
45 mph (72.42 km/h)48.95 mph (78.78 km/h)
50 mph (80.47 km/h)54.39 mph (87.54 km/h)
55 mph (88.51 km/h)59.83 mph (96.29 km/h)
60 mph (96.56 km/h)65.27 mph (105.04 km/h)
65 mph (104.61 km/h)70.71 mph (113.8 km/h)
70 mph (112.65 km/h)76.15 mph (122.55 km/h)
75 mph (120.7 km/h)81.59 mph (131.3 km/h)
80 mph (128.75 km/h)87.03 mph (140.06 km/h)
85 mph (136.79 km/h)92.47 mph (148.81 km/h)
90 mph (144.84 km/h)97.91 mph (157.57 km/h)
95 mph (152.89 km/h)103.35 mph (166.32 km/h)
100 mph (160.93 km/h)108.79 mph (175.07 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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