Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
170/80r16 vs 170/85r15 Tire Comparison Side By Side
  170/80-16 170/85-15 Difference
Diameter inches (mm) 26.71 (678.4) 26.38 (670) -0.33 (-8.4) -1.2%
Width inches (mm) 6.69 (170) 6.69 (170) 0 (0) 0%
Circum. inches (mm) 83.91 (2131.26) 82.87 (2104.87) -1.04 (-26.39) -1.2%
Sidewall Height inches (mm) 5.35 (136) 5.69 (144.5) 0.33 (8.5) 6.3%
Revolutions per mile (km) 755.12 (469.21) 764.58 (475.09) 9.47 (5.88) 1.3%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.75 mph (31.79 km/h)
25 mph (40.23 km/h)24.69 mph (39.74 km/h)
30 mph (48.28 km/h)29.63 mph (47.68 km/h)
35 mph (56.33 km/h)34.57 mph (55.63 km/h)
40 mph (64.37 km/h)39.5 mph (63.58 km/h)
45 mph (72.42 km/h)44.44 mph (71.52 km/h)
50 mph (80.47 km/h)49.38 mph (79.47 km/h)
55 mph (88.51 km/h)54.32 mph (87.42 km/h)
60 mph (96.56 km/h)59.26 mph (95.37 km/h)
65 mph (104.61 km/h)64.2 mph (103.31 km/h)
70 mph (112.65 km/h)69.13 mph (111.26 km/h)
75 mph (120.7 km/h)74.07 mph (119.21 km/h)
80 mph (128.75 km/h)79.01 mph (127.15 km/h)
85 mph (136.79 km/h)83.95 mph (135.1 km/h)
90 mph (144.84 km/h)88.89 mph (143.05 km/h)
95 mph (152.89 km/h)93.82 mph (150.99 km/h)
100 mph (160.93 km/h)98.76 mph (158.94 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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