Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
275/40r21 vs 275/40r20 Tire Comparison Side By Side
  275/40-21 275/40-20 Difference
Diameter inches (mm) 29.66 (753.4) 28.66 (728) -1 (-25.4) -3.4%
Width inches (mm) 10.83 (275) 10.83 (275) 0 (0) 0%
Circum. inches (mm) 93.18 (2366.88) 90.04 (2287.08) -3.14 (-79.8) -3.4%
Sidewall Height inches (mm) 4.33 (110) 4.33 (110) 0 (0) 0%
Revolutions per mile (km) 679.94 (422.5) 703.67 (437.24) 23.72 (14.74) 3.5%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.33 mph (31.1 km/h)
25 mph (40.23 km/h)24.16 mph (38.88 km/h)
30 mph (48.28 km/h)28.99 mph (46.65 km/h)
35 mph (56.33 km/h)33.82 mph (54.43 km/h)
40 mph (64.37 km/h)38.65 mph (62.2 km/h)
45 mph (72.42 km/h)43.48 mph (69.98 km/h)
50 mph (80.47 km/h)48.31 mph (77.75 km/h)
55 mph (88.51 km/h)53.15 mph (85.53 km/h)
60 mph (96.56 km/h)57.98 mph (93.31 km/h)
65 mph (104.61 km/h)62.81 mph (101.08 km/h)
70 mph (112.65 km/h)67.64 mph (108.86 km/h)
75 mph (120.7 km/h)72.47 mph (116.63 km/h)
80 mph (128.75 km/h)77.3 mph (124.41 km/h)
85 mph (136.79 km/h)82.13 mph (132.18 km/h)
90 mph (144.84 km/h)86.97 mph (139.96 km/h)
95 mph (152.89 km/h)91.8 mph (147.73 km/h)
100 mph (160.93 km/h)96.63 mph (155.51 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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