Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
135/80r18 vs 135/70r18 Tire Comparison Side By Side
  135/80-18 135/70-18 Difference
Diameter inches (mm) 26.5 (673.2) 25.44 (646.2) -1.06 (-27) -4%
Width inches (mm) 5.31 (135) 5.31 (135) 0 (0) 0%
Circum. inches (mm) 83.26 (2114.92) 79.93 (2030.1) -3.34 (-84.82) -4%
Sidewall Height inches (mm) 4.25 (108) 3.72 (94.5) -0.53 (-13.5) -12.5%
Revolutions per mile (km) 760.95 (472.83) 792.74 (492.59) 31.79 (19.76) 4.2%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.2 mph (30.9 km/h)
25 mph (40.23 km/h)24 mph (38.62 km/h)
30 mph (48.28 km/h)28.8 mph (46.34 km/h)
35 mph (56.33 km/h)33.6 mph (54.07 km/h)
40 mph (64.37 km/h)38.4 mph (61.79 km/h)
45 mph (72.42 km/h)43.2 mph (69.52 km/h)
50 mph (80.47 km/h)47.99 mph (77.24 km/h)
55 mph (88.51 km/h)52.79 mph (84.96 km/h)
60 mph (96.56 km/h)57.59 mph (92.69 km/h)
65 mph (104.61 km/h)62.39 mph (100.41 km/h)
70 mph (112.65 km/h)67.19 mph (108.14 km/h)
75 mph (120.7 km/h)71.99 mph (115.86 km/h)
80 mph (128.75 km/h)76.79 mph (123.58 km/h)
85 mph (136.79 km/h)81.59 mph (131.31 km/h)
90 mph (144.84 km/h)86.39 mph (139.03 km/h)
95 mph (152.89 km/h)91.19 mph (146.76 km/h)
100 mph (160.93 km/h)95.99 mph (154.48 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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