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 275/40r21 Tire Comparison Side By Side
  245/40-21 275/40-21 Difference
Diameter inches (mm) 28.72 (729.4) 29.66 (753.4) 0.94 (24) 3.3%
Width inches (mm) 9.65 (245) 10.83 (275) 1.18 (30) 12.2%
Circum. inches (mm) 90.22 (2291.48) 93.18 (2366.88) 2.97 (75.4) 3.3%
Sidewall Height inches (mm) 3.86 (98) 4.33 (110) 0.47 (12) 12.2%
Revolutions per mile (km) 702.32 (436.4) 679.94 (422.5) -22.37 (-13.9) -3.2%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.66 mph (33.25 km/h)
25 mph (40.23 km/h)25.82 mph (41.56 km/h)
30 mph (48.28 km/h)30.99 mph (49.87 km/h)
35 mph (56.33 km/h)36.15 mph (58.18 km/h)
40 mph (64.37 km/h)41.32 mph (66.49 km/h)
45 mph (72.42 km/h)46.48 mph (74.8 km/h)
50 mph (80.47 km/h)51.65 mph (83.12 km/h)
55 mph (88.51 km/h)56.81 mph (91.43 km/h)
60 mph (96.56 km/h)61.97 mph (99.74 km/h)
65 mph (104.61 km/h)67.14 mph (108.05 km/h)
70 mph (112.65 km/h)72.3 mph (116.36 km/h)
75 mph (120.7 km/h)77.47 mph (124.67 km/h)
80 mph (128.75 km/h)82.63 mph (132.98 km/h)
85 mph (136.79 km/h)87.8 mph (141.3 km/h)
90 mph (144.84 km/h)92.96 mph (149.61 km/h)
95 mph (152.89 km/h)98.13 mph (157.92 km/h)
100 mph (160.93 km/h)103.29 mph (166.23 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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