Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
265/30r21 vs 285/30r20 Tire Comparison Side By Side
  265/30-21 285/30-20 Difference
Diameter inches (mm) 27.26 (692.4) 26.73 (679) -0.53 (-13.4) -1.9%
Width inches (mm) 10.43 (265) 11.22 (285) 0.79 (20) 7.5%
Circum. inches (mm) 85.64 (2175.24) 83.98 (2133.14) -1.66 (-42.1) -1.9%
Sidewall Height inches (mm) 3.13 (79.5) 3.37 (85.5) 0.24 (6) 7.5%
Revolutions per mile (km) 739.85 (459.72) 754.45 (468.79) 14.6 (9.07) 2%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.61 mph (31.56 km/h)
25 mph (40.23 km/h)24.52 mph (39.46 km/h)
30 mph (48.28 km/h)29.42 mph (47.35 km/h)
35 mph (56.33 km/h)34.32 mph (55.24 km/h)
40 mph (64.37 km/h)39.23 mph (63.13 km/h)
45 mph (72.42 km/h)44.13 mph (71.02 km/h)
50 mph (80.47 km/h)49.03 mph (78.91 km/h)
55 mph (88.51 km/h)53.94 mph (86.8 km/h)
60 mph (96.56 km/h)58.84 mph (94.69 km/h)
65 mph (104.61 km/h)63.74 mph (102.58 km/h)
70 mph (112.65 km/h)68.65 mph (110.47 km/h)
75 mph (120.7 km/h)73.55 mph (118.37 km/h)
80 mph (128.75 km/h)78.45 mph (126.26 km/h)
85 mph (136.79 km/h)83.35 mph (134.15 km/h)
90 mph (144.84 km/h)88.26 mph (142.04 km/h)
95 mph (152.89 km/h)93.16 mph (149.93 km/h)
100 mph (160.93 km/h)98.06 mph (157.82 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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