Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
325/25r21 vs 255/35r20 Tire Comparison Side By Side
  325/25-21 255/35-20 Difference
Diameter inches (mm) 27.4 (695.9) 27.03 (686.5) -0.37 (-9.4) -1.4%
Width inches (mm) 12.8 (325) 10.04 (255) -2.76 (-70) -21.5%
Circum. inches (mm) 86.07 (2186.23) 84.91 (2156.7) -1.16 (-29.53) -1.4%
Sidewall Height inches (mm) 3.2 (81.25) 3.51 (89.25) 0.31 (8) 9.8%
Revolutions per mile (km) 736.13 (457.41) 746.21 (463.67) 10.08 (6.26) 1.4%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.73 mph (31.75 km/h)
25 mph (40.23 km/h)24.66 mph (39.69 km/h)
30 mph (48.28 km/h)29.59 mph (47.63 km/h)
35 mph (56.33 km/h)34.53 mph (55.57 km/h)
40 mph (64.37 km/h)39.46 mph (63.5 km/h)
45 mph (72.42 km/h)44.39 mph (71.44 km/h)
50 mph (80.47 km/h)49.32 mph (79.38 km/h)
55 mph (88.51 km/h)54.26 mph (87.32 km/h)
60 mph (96.56 km/h)59.19 mph (95.26 km/h)
65 mph (104.61 km/h)64.12 mph (103.19 km/h)
70 mph (112.65 km/h)69.05 mph (111.13 km/h)
75 mph (120.7 km/h)73.99 mph (119.07 km/h)
80 mph (128.75 km/h)78.92 mph (127.01 km/h)
85 mph (136.79 km/h)83.85 mph (134.95 km/h)
90 mph (144.84 km/h)88.78 mph (142.88 km/h)
95 mph (152.89 km/h)93.72 mph (150.82 km/h)
100 mph (160.93 km/h)98.65 mph (158.76 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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