Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
355/25r21 vs 325/30r20 Tire Comparison Side By Side
  355/25-21 325/30-20 Difference
Diameter inches (mm) 27.99 (710.9) 27.68 (703) -0.31 (-7.9) -1.1%
Width inches (mm) 13.98 (355) 12.8 (325) -1.18 (-30) -8.5%
Circum. inches (mm) 87.93 (2233.36) 86.95 (2208.54) -0.98 (-24.82) -1.1%
Sidewall Height inches (mm) 3.49 (88.75) 3.84 (97.5) 0.34 (8.75) 9.9%
Revolutions per mile (km) 720.59 (447.76) 728.69 (452.79) 8.1 (5.03) 1.1%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.78 mph (31.83 km/h)
25 mph (40.23 km/h)24.72 mph (39.79 km/h)
30 mph (48.28 km/h)29.67 mph (47.74 km/h)
35 mph (56.33 km/h)34.61 mph (55.7 km/h)
40 mph (64.37 km/h)39.56 mph (63.66 km/h)
45 mph (72.42 km/h)44.5 mph (71.62 km/h)
50 mph (80.47 km/h)49.44 mph (79.57 km/h)
55 mph (88.51 km/h)54.39 mph (87.53 km/h)
60 mph (96.56 km/h)59.33 mph (95.49 km/h)
65 mph (104.61 km/h)64.28 mph (103.45 km/h)
70 mph (112.65 km/h)69.22 mph (111.4 km/h)
75 mph (120.7 km/h)74.17 mph (119.36 km/h)
80 mph (128.75 km/h)79.11 mph (127.32 km/h)
85 mph (136.79 km/h)84.06 mph (135.27 km/h)
90 mph (144.84 km/h)89 mph (143.23 km/h)
95 mph (152.89 km/h)93.94 mph (151.19 km/h)
100 mph (160.93 km/h)98.89 mph (159.15 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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