Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
235/70r18 vs 235/65r18 Tire Comparison Side By Side
  235/70-18 235/65-18 Difference
Diameter inches (mm) 30.95 (786.2) 30.03 (762.7) -0.93 (-23.5) -3%
Width inches (mm) 9.25 (235) 9.25 (235) 0 (0) 0%
Circum. inches (mm) 97.24 (2469.92) 94.33 (2396.09) -2.91 (-73.83) -3%
Sidewall Height inches (mm) 6.48 (164.5) 6.01 (152.75) -0.46 (-11.75) -7.1%
Revolutions per mile (km) 651.58 (404.87) 671.65 (417.35) 20.08 (12.47) 3.1%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.4 mph (31.22 km/h)
25 mph (40.23 km/h)24.25 mph (39.03 km/h)
30 mph (48.28 km/h)29.1 mph (46.84 km/h)
35 mph (56.33 km/h)33.95 mph (54.64 km/h)
40 mph (64.37 km/h)38.8 mph (62.45 km/h)
45 mph (72.42 km/h)43.65 mph (70.26 km/h)
50 mph (80.47 km/h)48.51 mph (78.06 km/h)
55 mph (88.51 km/h)53.36 mph (85.87 km/h)
60 mph (96.56 km/h)58.21 mph (93.67 km/h)
65 mph (104.61 km/h)63.06 mph (101.48 km/h)
70 mph (112.65 km/h)67.91 mph (109.29 km/h)
75 mph (120.7 km/h)72.76 mph (117.09 km/h)
80 mph (128.75 km/h)77.61 mph (124.9 km/h)
85 mph (136.79 km/h)82.46 mph (132.71 km/h)
90 mph (144.84 km/h)87.31 mph (140.51 km/h)
95 mph (152.89 km/h)92.16 mph (148.32 km/h)
100 mph (160.93 km/h)97.01 mph (156.12 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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