Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
305/30r21 vs 245/35r21 Tire Comparison Side By Side
  305/30-21 245/35-21 Difference
Diameter inches (mm) 28.2 (716.4) 27.75 (704.9) -0.45 (-11.5) -1.6%
Width inches (mm) 12.01 (305) 9.65 (245) -2.36 (-60) -19.7%
Circum. inches (mm) 88.61 (2250.64) 87.19 (2214.51) -1.42 (-36.13) -1.6%
Sidewall Height inches (mm) 3.6 (91.5) 3.38 (85.75) -0.23 (-5.75) -6.3%
Revolutions per mile (km) 715.06 (444.32) 726.73 (451.57) 11.67 (7.25) 1.6%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.68 mph (31.67 km/h)
25 mph (40.23 km/h)24.6 mph (39.59 km/h)
30 mph (48.28 km/h)29.52 mph (47.51 km/h)
35 mph (56.33 km/h)34.44 mph (55.42 km/h)
40 mph (64.37 km/h)39.36 mph (63.34 km/h)
45 mph (72.42 km/h)44.28 mph (71.26 km/h)
50 mph (80.47 km/h)49.2 mph (79.18 km/h)
55 mph (88.51 km/h)54.12 mph (87.09 km/h)
60 mph (96.56 km/h)59.04 mph (95.01 km/h)
65 mph (104.61 km/h)63.96 mph (102.93 km/h)
70 mph (112.65 km/h)68.88 mph (110.85 km/h)
75 mph (120.7 km/h)73.8 mph (118.76 km/h)
80 mph (128.75 km/h)78.72 mph (126.68 km/h)
85 mph (136.79 km/h)83.64 mph (134.6 km/h)
90 mph (144.84 km/h)88.56 mph (142.52 km/h)
95 mph (152.89 km/h)93.48 mph (150.43 km/h)
100 mph (160.93 km/h)98.39 mph (158.35 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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