Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
235/45r18 vs 245/35r20 Tire Comparison Side By Side
  235/45-18 245/35-20 Difference
Diameter inches (mm) 26.33 (668.7) 26.75 (679.5) 0.43 (10.8) 1.6%
Width inches (mm) 9.25 (235) 9.65 (245) 0.39 (10) 4.3%
Circum. inches (mm) 82.71 (2100.78) 84.04 (2134.71) 1.34 (33.93) 1.6%
Sidewall Height inches (mm) 4.16 (105.75) 3.38 (85.75) -0.79 (-20) -18.9%
Revolutions per mile (km) 766.07 (476.01) 753.89 (468.45) -12.18 (-7.57) -1.6%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.32 mph (32.71 km/h)
25 mph (40.23 km/h)25.4 mph (40.88 km/h)
30 mph (48.28 km/h)30.48 mph (49.06 km/h)
35 mph (56.33 km/h)35.57 mph (57.24 km/h)
40 mph (64.37 km/h)40.65 mph (65.41 km/h)
45 mph (72.42 km/h)45.73 mph (73.59 km/h)
50 mph (80.47 km/h)50.81 mph (81.77 km/h)
55 mph (88.51 km/h)55.89 mph (89.94 km/h)
60 mph (96.56 km/h)60.97 mph (98.12 km/h)
65 mph (104.61 km/h)66.05 mph (106.3 km/h)
70 mph (112.65 km/h)71.13 mph (114.47 km/h)
75 mph (120.7 km/h)76.21 mph (122.65 km/h)
80 mph (128.75 km/h)81.29 mph (130.83 km/h)
85 mph (136.79 km/h)86.37 mph (139 km/h)
90 mph (144.84 km/h)91.45 mph (147.18 km/h)
95 mph (152.89 km/h)96.53 mph (155.36 km/h)
100 mph (160.93 km/h)101.62 mph (163.53 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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