Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
135/80r12 vs 145/65r13 Tire Comparison Side By Side
  135/80-12 145/65-13 Difference
Diameter inches (mm) 20.5 (520.8) 20.42 (518.7) -0.08 (-2.1) -0.4%
Width inches (mm) 5.31 (135) 5.71 (145) 0.39 (10) 7.4%
Circum. inches (mm) 64.42 (1636.14) 64.16 (1629.54) -0.26 (-6.6) -0.4%
Sidewall Height inches (mm) 4.25 (108) 3.71 (94.25) -0.54 (-13.75) -12.7%
Revolutions per mile (km) 983.62 (611.19) 987.6 (613.67) 3.98 (2.47) 0.4%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.92 mph (32.06 km/h)
25 mph (40.23 km/h)24.9 mph (40.07 km/h)
30 mph (48.28 km/h)29.88 mph (48.09 km/h)
35 mph (56.33 km/h)34.86 mph (56.1 km/h)
40 mph (64.37 km/h)39.84 mph (64.11 km/h)
45 mph (72.42 km/h)44.82 mph (72.13 km/h)
50 mph (80.47 km/h)49.8 mph (80.14 km/h)
55 mph (88.51 km/h)54.78 mph (88.16 km/h)
60 mph (96.56 km/h)59.76 mph (96.17 km/h)
65 mph (104.61 km/h)64.74 mph (104.19 km/h)
70 mph (112.65 km/h)69.72 mph (112.2 km/h)
75 mph (120.7 km/h)74.7 mph (120.21 km/h)
80 mph (128.75 km/h)79.68 mph (128.23 km/h)
85 mph (136.79 km/h)84.66 mph (136.24 km/h)
90 mph (144.84 km/h)89.64 mph (144.26 km/h)
95 mph (152.89 km/h)94.62 mph (152.27 km/h)
100 mph (160.93 km/h)99.6 mph (160.29 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
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
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