Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
285/50r18 vs 33/12.5r18 Tire Comparison Side By Side
  285/50-18 33/12.5-18 Difference
Diameter inches (mm) 29.22 (742.2) 33.02 (838.8) 3.8 (96.6) 13%
Width inches (mm) 11.22 (285) 12.52 (318) 1.3 (33) 11.6%
Circum. inches (mm) 91.8 (2331.69) 103.75 (2635.17) 11.95 (303.48) 13%
Sidewall Height inches (mm) 5.61 (142.5) 7.51 (190.8) 1.9 (48.3) 33.9%
Revolutions per mile (km) 690.2 (428.87) 610.72 (379.48) -79.49 (-49.39) -11.5%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)22.6 mph (36.38 km/h)
25 mph (40.23 km/h)28.25 mph (45.47 km/h)
30 mph (48.28 km/h)33.9 mph (54.56 km/h)
35 mph (56.33 km/h)39.56 mph (63.66 km/h)
40 mph (64.37 km/h)45.21 mph (72.75 km/h)
45 mph (72.42 km/h)50.86 mph (81.85 km/h)
50 mph (80.47 km/h)56.51 mph (90.94 km/h)
55 mph (88.51 km/h)62.16 mph (100.03 km/h)
60 mph (96.56 km/h)67.81 mph (109.13 km/h)
65 mph (104.61 km/h)73.46 mph (118.22 km/h)
70 mph (112.65 km/h)79.11 mph (127.32 km/h)
75 mph (120.7 km/h)84.76 mph (136.41 km/h)
80 mph (128.75 km/h)90.41 mph (145.5 km/h)
85 mph (136.79 km/h)96.06 mph (154.6 km/h)
90 mph (144.84 km/h)101.71 mph (163.69 km/h)
95 mph (152.89 km/h)107.36 mph (172.79 km/h)
100 mph (160.93 km/h)113.02 mph (181.88 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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