Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
325/60r15 vs 30/10.5r15 Tire Comparison Side By Side
  325/60-15 30/10.5-15 Difference
Diameter inches (mm) 30.35 (771) 29.93 (760.14) -0.43 (-10.86) -1.4%
Width inches (mm) 12.8 (325) 10.51 (267) -2.28 (-58) -17.8%
Circum. inches (mm) 95.36 (2422.17) 94.02 (2388.05) -1.34 (-34.12) -1.4%
Sidewall Height inches (mm) 7.68 (195) 7.46 (189.57) -0.21 (-5.43) -2.8%
Revolutions per mile (km) 664.42 (412.85) 673.92 (418.75) 9.49 (5.9) 1.4%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.72 mph (31.73 km/h)
25 mph (40.23 km/h)24.65 mph (39.67 km/h)
30 mph (48.28 km/h)29.58 mph (47.6 km/h)
35 mph (56.33 km/h)34.51 mph (55.53 km/h)
40 mph (64.37 km/h)39.44 mph (63.47 km/h)
45 mph (72.42 km/h)44.37 mph (71.4 km/h)
50 mph (80.47 km/h)49.3 mph (79.33 km/h)
55 mph (88.51 km/h)54.23 mph (87.27 km/h)
60 mph (96.56 km/h)59.15 mph (95.2 km/h)
65 mph (104.61 km/h)64.08 mph (103.13 km/h)
70 mph (112.65 km/h)69.01 mph (111.07 km/h)
75 mph (120.7 km/h)73.94 mph (119 km/h)
80 mph (128.75 km/h)78.87 mph (126.93 km/h)
85 mph (136.79 km/h)83.8 mph (134.87 km/h)
90 mph (144.84 km/h)88.73 mph (142.8 km/h)
95 mph (152.89 km/h)93.66 mph (150.73 km/h)
100 mph (160.93 km/h)98.59 mph (158.67 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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