Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
120/70r15 vs 90/90r15 Tire Comparison Side By Side
  120/70-15 90/90-15 Difference
Diameter inches (mm) 21.61 (549) 21.38 (543) -0.24 (-6) -1.1%
Width inches (mm) 4.72 (120) 3.54 (90) -1.18 (-30) -25%
Circum. inches (mm) 67.9 (1724.73) 67.16 (1705.88) -0.74 (-18.85) -1.1%
Sidewall Height inches (mm) 3.31 (84) 3.19 (81) -0.12 (-3) -3.6%
Revolutions per mile (km) 933.1 (579.8) 943.41 (586.2) 10.31 (6.41) 1.1%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.78 mph (31.84 km/h)
25 mph (40.23 km/h)24.73 mph (39.79 km/h)
30 mph (48.28 km/h)29.67 mph (47.75 km/h)
35 mph (56.33 km/h)34.62 mph (55.71 km/h)
40 mph (64.37 km/h)39.56 mph (63.67 km/h)
45 mph (72.42 km/h)44.51 mph (71.63 km/h)
50 mph (80.47 km/h)49.45 mph (79.59 km/h)
55 mph (88.51 km/h)54.4 mph (87.55 km/h)
60 mph (96.56 km/h)59.34 mph (95.51 km/h)
65 mph (104.61 km/h)64.29 mph (103.46 km/h)
70 mph (112.65 km/h)69.23 mph (111.42 km/h)
75 mph (120.7 km/h)74.18 mph (119.38 km/h)
80 mph (128.75 km/h)79.13 mph (127.34 km/h)
85 mph (136.79 km/h)84.07 mph (135.3 km/h)
90 mph (144.84 km/h)89.02 mph (143.26 km/h)
95 mph (152.89 km/h)93.96 mph (151.22 km/h)
100 mph (160.93 km/h)98.91 mph (159.18 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
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
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