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 355/30r20 Tire Comparison Side By Side
  355/25-21 355/30-20 Difference
Diameter inches (mm) 27.99 (710.9) 28.39 (721) 0.4 (10.1) 1.4%
Width inches (mm) 13.98 (355) 13.98 (355) 0 (0) 0%
Circum. inches (mm) 87.93 (2233.36) 89.18 (2265.09) 1.25 (31.73) 1.4%
Sidewall Height inches (mm) 3.49 (88.75) 4.19 (106.5) 0.7 (17.75) 20%
Revolutions per mile (km) 720.59 (447.76) 710.5 (441.48) -10.09 (-6.27) -1.4%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.28 mph (32.64 km/h)
25 mph (40.23 km/h)25.36 mph (40.81 km/h)
30 mph (48.28 km/h)30.43 mph (48.97 km/h)
35 mph (56.33 km/h)35.5 mph (57.13 km/h)
40 mph (64.37 km/h)40.57 mph (65.29 km/h)
45 mph (72.42 km/h)45.64 mph (73.45 km/h)
50 mph (80.47 km/h)50.71 mph (81.61 km/h)
55 mph (88.51 km/h)55.78 mph (89.77 km/h)
60 mph (96.56 km/h)60.85 mph (97.93 km/h)
65 mph (104.61 km/h)65.92 mph (106.09 km/h)
70 mph (112.65 km/h)70.99 mph (114.25 km/h)
75 mph (120.7 km/h)76.07 mph (122.42 km/h)
80 mph (128.75 km/h)81.14 mph (130.58 km/h)
85 mph (136.79 km/h)86.21 mph (138.74 km/h)
90 mph (144.84 km/h)91.28 mph (146.9 km/h)
95 mph (152.89 km/h)96.35 mph (155.06 km/h)
100 mph (160.93 km/h)101.42 mph (163.22 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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