Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
245/40r20 vs 305/35r20 Tire Comparison Side By Side
  245/40-20 305/35-20 Difference
Diameter inches (mm) 27.72 (704) 28.41 (721.5) 0.69 (17.5) 2.5%
Width inches (mm) 9.65 (245) 12.01 (305) 2.36 (60) 24.5%
Circum. inches (mm) 87.07 (2211.68) 89.24 (2266.66) 2.16 (54.98) 2.5%
Sidewall Height inches (mm) 3.86 (98) 4.2 (106.75) 0.34 (8.75) 8.9%
Revolutions per mile (km) 727.66 (452.14) 710.01 (441.18) -17.65 (-10.97) -2.4%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.5 mph (32.99 km/h)
25 mph (40.23 km/h)25.62 mph (41.23 km/h)
30 mph (48.28 km/h)30.75 mph (49.48 km/h)
35 mph (56.33 km/h)35.87 mph (57.73 km/h)
40 mph (64.37 km/h)40.99 mph (65.97 km/h)
45 mph (72.42 km/h)46.12 mph (74.22 km/h)
50 mph (80.47 km/h)51.24 mph (82.47 km/h)
55 mph (88.51 km/h)56.37 mph (90.71 km/h)
60 mph (96.56 km/h)61.49 mph (98.96 km/h)
65 mph (104.61 km/h)66.62 mph (107.21 km/h)
70 mph (112.65 km/h)71.74 mph (115.45 km/h)
75 mph (120.7 km/h)76.86 mph (123.7 km/h)
80 mph (128.75 km/h)81.99 mph (131.95 km/h)
85 mph (136.79 km/h)87.11 mph (140.19 km/h)
90 mph (144.84 km/h)92.24 mph (148.44 km/h)
95 mph (152.89 km/h)97.36 mph (156.69 km/h)
100 mph (160.93 km/h)102.49 mph (164.94 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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