Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
235/40r18 vs 245/40r18 Tire Comparison Side By Side
  235/40-18 245/40-18 Difference
Diameter inches (mm) 25.4 (645.2) 25.72 (653.2) 0.31 (8) 1.2%
Width inches (mm) 9.25 (235) 9.65 (245) 0.39 (10) 4.3%
Circum. inches (mm) 79.8 (2026.96) 80.79 (2052.09) 0.99 (25.13) 1.2%
Sidewall Height inches (mm) 3.7 (94) 3.86 (98) 0.16 (4) 4.3%
Revolutions per mile (km) 793.97 (493.35) 784.25 (487.31) -9.72 (-6.04) -1.2%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.25 mph (32.59 km/h)
25 mph (40.23 km/h)25.31 mph (40.73 km/h)
30 mph (48.28 km/h)30.37 mph (48.88 km/h)
35 mph (56.33 km/h)35.43 mph (57.03 km/h)
40 mph (64.37 km/h)40.5 mph (65.17 km/h)
45 mph (72.42 km/h)45.56 mph (73.32 km/h)
50 mph (80.47 km/h)50.62 mph (81.47 km/h)
55 mph (88.51 km/h)55.68 mph (89.61 km/h)
60 mph (96.56 km/h)60.74 mph (97.76 km/h)
65 mph (104.61 km/h)65.81 mph (105.9 km/h)
70 mph (112.65 km/h)70.87 mph (114.05 km/h)
75 mph (120.7 km/h)75.93 mph (122.2 km/h)
80 mph (128.75 km/h)80.99 mph (130.34 km/h)
85 mph (136.79 km/h)86.05 mph (138.49 km/h)
90 mph (144.84 km/h)91.12 mph (146.64 km/h)
95 mph (152.89 km/h)96.18 mph (154.78 km/h)
100 mph (160.93 km/h)101.24 mph (162.93 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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