Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
145/65r15 vs 145/40r15 Tire Comparison Side By Side
  145/65-15 145/40-15 Difference
Diameter inches (mm) 22.42 (569.5) 19.57 (497) -2.85 (-72.5) -12.7%
Width inches (mm) 5.71 (145) 5.71 (145) 0 (0) 0%
Circum. inches (mm) 70.44 (1789.14) 61.47 (1561.37) -8.97 (-227.77) -12.7%
Sidewall Height inches (mm) 3.71 (94.25) 2.28 (58) -1.43 (-36.25) -38.5%
Revolutions per mile (km) 899.51 (558.93) 1030.72 (640.46) 131.22 (81.53) 14.6%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)17.45 mph (28.09 km/h)
25 mph (40.23 km/h)21.82 mph (35.11 km/h)
30 mph (48.28 km/h)26.18 mph (42.13 km/h)
35 mph (56.33 km/h)30.54 mph (49.16 km/h)
40 mph (64.37 km/h)34.91 mph (56.18 km/h)
45 mph (72.42 km/h)39.27 mph (63.2 km/h)
50 mph (80.47 km/h)43.63 mph (70.22 km/h)
55 mph (88.51 km/h)48 mph (77.25 km/h)
60 mph (96.56 km/h)52.36 mph (84.27 km/h)
65 mph (104.61 km/h)56.73 mph (91.29 km/h)
70 mph (112.65 km/h)61.09 mph (98.31 km/h)
75 mph (120.7 km/h)65.45 mph (105.34 km/h)
80 mph (128.75 km/h)69.82 mph (112.36 km/h)
85 mph (136.79 km/h)74.18 mph (119.38 km/h)
90 mph (144.84 km/h)78.54 mph (126.4 km/h)
95 mph (152.89 km/h)82.91 mph (133.42 km/h)
100 mph (160.93 km/h)87.27 mph (140.45 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
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
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