Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
235/50r18 vs 245/40r18 Tire Comparison Side By Side
  235/50-18 245/40-18 Difference
Diameter inches (mm) 27.25 (692.2) 25.72 (653.2) -1.54 (-39) -5.6%
Width inches (mm) 9.25 (235) 9.65 (245) 0.39 (10) 4.3%
Circum. inches (mm) 85.61 (2174.61) 80.79 (2052.09) -4.82 (-122.52) -5.6%
Sidewall Height inches (mm) 4.63 (117.5) 3.86 (98) -0.77 (-19.5) -16.6%
Revolutions per mile (km) 740.06 (459.85) 784.25 (487.31) 44.19 (27.46) 6%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)18.87 mph (30.37 km/h)
25 mph (40.23 km/h)23.59 mph (37.97 km/h)
30 mph (48.28 km/h)28.31 mph (45.56 km/h)
35 mph (56.33 km/h)33.03 mph (53.15 km/h)
40 mph (64.37 km/h)37.75 mph (60.75 km/h)
45 mph (72.42 km/h)42.46 mph (68.34 km/h)
50 mph (80.47 km/h)47.18 mph (75.93 km/h)
55 mph (88.51 km/h)51.9 mph (83.53 km/h)
60 mph (96.56 km/h)56.62 mph (91.12 km/h)
65 mph (104.61 km/h)61.34 mph (98.71 km/h)
70 mph (112.65 km/h)66.06 mph (106.31 km/h)
75 mph (120.7 km/h)70.77 mph (113.9 km/h)
80 mph (128.75 km/h)75.49 mph (121.49 km/h)
85 mph (136.79 km/h)80.21 mph (129.09 km/h)
90 mph (144.84 km/h)84.93 mph (136.68 km/h)
95 mph (152.89 km/h)89.65 mph (144.27 km/h)
100 mph (160.93 km/h)94.37 mph (151.87 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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