Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
305/45r20 vs 305/35r20 Tire Comparison Side By Side
  305/45-20 305/35-20 Difference
Diameter inches (mm) 30.81 (782.5) 28.41 (721.5) -2.4 (-61) -7.8%
Width inches (mm) 12.01 (305) 12.01 (305) 0 (0) 0%
Circum. inches (mm) 96.78 (2458.3) 89.24 (2266.66) -7.54 (-191.64) -7.8%
Sidewall Height inches (mm) 5.4 (137.25) 4.2 (106.75) -1.2 (-30.5) -22.2%
Revolutions per mile (km) 654.66 (406.79) 710.01 (441.18) 55.35 (34.39) 8.5%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)18.44 mph (29.68 km/h)
25 mph (40.23 km/h)23.05 mph (37.1 km/h)
30 mph (48.28 km/h)27.66 mph (44.52 km/h)
35 mph (56.33 km/h)32.27 mph (51.94 km/h)
40 mph (64.37 km/h)36.88 mph (59.36 km/h)
45 mph (72.42 km/h)41.49 mph (66.78 km/h)
50 mph (80.47 km/h)46.1 mph (74.19 km/h)
55 mph (88.51 km/h)50.71 mph (81.61 km/h)
60 mph (96.56 km/h)55.32 mph (89.03 km/h)
65 mph (104.61 km/h)59.93 mph (96.45 km/h)
70 mph (112.65 km/h)64.54 mph (103.87 km/h)
75 mph (120.7 km/h)69.15 mph (111.29 km/h)
80 mph (128.75 km/h)73.76 mph (118.71 km/h)
85 mph (136.79 km/h)78.37 mph (126.13 km/h)
90 mph (144.84 km/h)82.98 mph (133.55 km/h)
95 mph (152.89 km/h)87.59 mph (140.97 km/h)
100 mph (160.93 km/h)92.2 mph (148.39 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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