Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
305/40r20 vs 315/35r20 Tire Comparison Side By Side
  305/40-20 315/35-20 Difference
Diameter inches (mm) 29.61 (752) 28.68 (728.5) -0.93 (-23.5) -3.1%
Width inches (mm) 12.01 (305) 12.4 (315) 0.39 (10) 3.3%
Circum. inches (mm) 93.01 (2362.48) 90.1 (2288.65) -2.91 (-73.83) -3.1%
Sidewall Height inches (mm) 4.8 (122) 4.34 (110.25) -0.46 (-11.75) -9.6%
Revolutions per mile (km) 681.21 (423.28) 703.18 (436.94) 21.97 (13.65) 3.2%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.38 mph (31.18 km/h)
25 mph (40.23 km/h)24.22 mph (38.98 km/h)
30 mph (48.28 km/h)29.06 mph (46.77 km/h)
35 mph (56.33 km/h)33.91 mph (54.57 km/h)
40 mph (64.37 km/h)38.75 mph (62.36 km/h)
45 mph (72.42 km/h)43.59 mph (70.16 km/h)
50 mph (80.47 km/h)48.44 mph (77.95 km/h)
55 mph (88.51 km/h)53.28 mph (85.75 km/h)
60 mph (96.56 km/h)58.13 mph (93.54 km/h)
65 mph (104.61 km/h)62.97 mph (101.34 km/h)
70 mph (112.65 km/h)67.81 mph (109.13 km/h)
75 mph (120.7 km/h)72.66 mph (116.93 km/h)
80 mph (128.75 km/h)77.5 mph (124.72 km/h)
85 mph (136.79 km/h)82.34 mph (132.52 km/h)
90 mph (144.84 km/h)87.19 mph (140.31 km/h)
95 mph (152.89 km/h)92.03 mph (148.11 km/h)
100 mph (160.93 km/h)96.88 mph (155.91 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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