Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
235/30r18 vs 215/40r18 Tire Comparison Side By Side
  235/30-18 215/40-18 Difference
Diameter inches (mm) 23.55 (598.2) 24.77 (629.2) 1.22 (31) 5.2%
Width inches (mm) 9.25 (235) 8.46 (215) -0.79 (-20) -8.5%
Circum. inches (mm) 73.99 (1879.3) 77.82 (1976.69) 3.83 (97.39) 5.2%
Sidewall Height inches (mm) 2.78 (70.5) 3.39 (86) 0.61 (15.5) 22%
Revolutions per mile (km) 856.35 (532.11) 814.16 (505.9) -42.19 (-26.22) -4.9%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)21.04 mph (33.85 km/h)
25 mph (40.23 km/h)26.3 mph (42.32 km/h)
30 mph (48.28 km/h)31.55 mph (50.78 km/h)
35 mph (56.33 km/h)36.81 mph (59.25 km/h)
40 mph (64.37 km/h)42.07 mph (67.71 km/h)
45 mph (72.42 km/h)47.33 mph (76.17 km/h)
50 mph (80.47 km/h)52.59 mph (84.64 km/h)
55 mph (88.51 km/h)57.85 mph (93.1 km/h)
60 mph (96.56 km/h)63.11 mph (101.56 km/h)
65 mph (104.61 km/h)68.37 mph (110.03 km/h)
70 mph (112.65 km/h)73.63 mph (118.49 km/h)
75 mph (120.7 km/h)78.89 mph (126.96 km/h)
80 mph (128.75 km/h)84.15 mph (135.42 km/h)
85 mph (136.79 km/h)89.4 mph (143.88 km/h)
90 mph (144.84 km/h)94.66 mph (152.35 km/h)
95 mph (152.89 km/h)99.92 mph (160.81 km/h)
100 mph (160.93 km/h)105.18 mph (169.27 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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