Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
245/40r21 vs 245/35r21 Tire Comparison Side By Side
  245/40-21 245/35-21 Difference
Diameter inches (mm) 28.72 (729.4) 27.75 (704.9) -0.96 (-24.5) -3.4%
Width inches (mm) 9.65 (245) 9.65 (245) 0 (0) 0%
Circum. inches (mm) 90.22 (2291.48) 87.19 (2214.51) -3.03 (-76.97) -3.4%
Sidewall Height inches (mm) 3.86 (98) 3.38 (85.75) -0.48 (-12.25) -12.5%
Revolutions per mile (km) 702.32 (436.4) 726.73 (451.57) 24.41 (15.17) 3.5%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.33 mph (31.11 km/h)
25 mph (40.23 km/h)24.16 mph (38.88 km/h)
30 mph (48.28 km/h)28.99 mph (46.66 km/h)
35 mph (56.33 km/h)33.82 mph (54.44 km/h)
40 mph (64.37 km/h)38.66 mph (62.21 km/h)
45 mph (72.42 km/h)43.49 mph (69.99 km/h)
50 mph (80.47 km/h)48.32 mph (77.76 km/h)
55 mph (88.51 km/h)53.15 mph (85.54 km/h)
60 mph (96.56 km/h)57.98 mph (93.32 km/h)
65 mph (104.61 km/h)62.82 mph (101.09 km/h)
70 mph (112.65 km/h)67.65 mph (108.87 km/h)
75 mph (120.7 km/h)72.48 mph (116.65 km/h)
80 mph (128.75 km/h)77.31 mph (124.42 km/h)
85 mph (136.79 km/h)82.14 mph (132.2 km/h)
90 mph (144.84 km/h)86.98 mph (139.98 km/h)
95 mph (152.89 km/h)91.81 mph (147.75 km/h)
100 mph (160.93 km/h)96.64 mph (155.53 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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