Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
315/30r20 vs 345/25r20 Tire Comparison Side By Side
  315/30-20 345/25-20 Difference
Diameter inches (mm) 27.44 (697) 26.79 (680.5) -0.65 (-16.5) -2.4%
Width inches (mm) 12.4 (315) 13.58 (345) 1.18 (30) 9.5%
Circum. inches (mm) 86.21 (2189.69) 84.17 (2137.85) -2.04 (-51.84) -2.4%
Sidewall Height inches (mm) 3.72 (94.5) 3.4 (86.25) -0.32 (-8.25) -8.7%
Revolutions per mile (km) 734.96 (456.68) 752.78 (467.76) 17.82 (11.07) 2.4%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.53 mph (31.42 km/h)
25 mph (40.23 km/h)24.41 mph (39.28 km/h)
30 mph (48.28 km/h)29.29 mph (47.14 km/h)
35 mph (56.33 km/h)34.17 mph (54.99 km/h)
40 mph (64.37 km/h)39.05 mph (62.85 km/h)
45 mph (72.42 km/h)43.93 mph (70.71 km/h)
50 mph (80.47 km/h)48.82 mph (78.56 km/h)
55 mph (88.51 km/h)53.7 mph (86.42 km/h)
60 mph (96.56 km/h)58.58 mph (94.27 km/h)
65 mph (104.61 km/h)63.46 mph (102.13 km/h)
70 mph (112.65 km/h)68.34 mph (109.99 km/h)
75 mph (120.7 km/h)73.22 mph (117.84 km/h)
80 mph (128.75 km/h)78.11 mph (125.7 km/h)
85 mph (136.79 km/h)82.99 mph (133.56 km/h)
90 mph (144.84 km/h)87.87 mph (141.41 km/h)
95 mph (152.89 km/h)92.75 mph (149.27 km/h)
100 mph (160.93 km/h)97.63 mph (157.12 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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