Tire Size Calculator

Tire Size Finder (optional):

Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
235/55r20 vs 255/45r20 Tire Comparison Side By Side
  235/55-20 255/45-20 Difference
Diameter inches (mm) 30.18 (766.5) 29.04 (737.5) -1.14 (-29) -3.8%
Width inches (mm) 9.25 (235) 10.04 (255) 0.79 (20) 8.5%
Circum. inches (mm) 94.8 (2408.03) 91.22 (2316.92) -3.59 (-91.11) -3.8%
Sidewall Height inches (mm) 5.09 (129.25) 4.52 (114.75) -0.57 (-14.5) -11.2%
Revolutions per mile (km) 668.32 (415.28) 694.6 (431.61) 26.28 (16.33) 3.9%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.24 mph (30.97 km/h)
25 mph (40.23 km/h)24.05 mph (38.71 km/h)
30 mph (48.28 km/h)28.86 mph (46.45 km/h)
35 mph (56.33 km/h)33.68 mph (54.2 km/h)
40 mph (64.37 km/h)38.49 mph (61.94 km/h)
45 mph (72.42 km/h)43.3 mph (69.68 km/h)
50 mph (80.47 km/h)48.11 mph (77.42 km/h)
55 mph (88.51 km/h)52.92 mph (85.17 km/h)
60 mph (96.56 km/h)57.73 mph (92.91 km/h)
65 mph (104.61 km/h)62.54 mph (100.65 km/h)
70 mph (112.65 km/h)67.35 mph (108.39 km/h)
75 mph (120.7 km/h)72.16 mph (116.13 km/h)
80 mph (128.75 km/h)76.97 mph (123.88 km/h)
85 mph (136.79 km/h)81.78 mph (131.62 km/h)
90 mph (144.84 km/h)86.59 mph (139.36 km/h)
95 mph (152.89 km/h)91.41 mph (147.1 km/h)
100 mph (160.93 km/h)96.22 mph (154.85 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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