This is using a 205/45/17 tire
Top speed = R / T * C
R = RPM (
7200)
T = Tranny ratio
C = Circumference of your tire
((((205mm * .45) / 10 / 2.54) *2) + 17in) * pi = 76.227 in =
6.352 ft
205mm is the width of the tire
.50 is the aspect ratio, which is the relationship between the tire's height and it's width
/ 10 is to convert from mm to cm
/ 2.54 is to convert from cm to in
* 2 for both sides of the rim
17 is the size of the rim
the total Diameter of the tire is 24.263 in
using the formula C = D pi
1st Gear
T = 3.307 (1st gear) * 4.105 (final gear) =
13.575
2nd Gear
T = 1.842 (2nd gear) * 4.105 (final gear) =
7.561
3rd Gear
T = 1.310 (3rd gear) * 4.105 (final gear) =
5.378
4th Gear
T = 0.970 (4th gear) * 4.105 (final gear) =
3.982
5th Gear
T = 0.755 (5th gear) * 4.105 (final gear) =
3.099
1st
R / T = 530.387 RPM (at the wheels) * 60 min = 31,823.204 RPH (at the wheels)
Top speed = 31,823.204 RPH * 6.352 ft = 202,140.994 ft/hr =
38.284 mph
2nd
R / T = 952.255 RPM (at the wheels) * 60 min = 57,135.300 RPH (at the wheels)
Top speed = 57,135.300 RPH * 6.352 ft = 362,923.423 ft/hr =
68.735 mph
3rd
R / T = 1338.788 RPM (at the wheels) * 60 min = 80,327.259 RPH (at the wheels)
Top speed = 80,327.259 RPH * 6.352 ft = 510,238.750 ft/hr =
96.636 mph
4th
R / T = 1808.137 RPM (at the wheels) * 60 min = 108,488.197 RPH (at the wheels)
Top speed = 108,488.197 RPH * 6.352 ft = 689,117.027 ft/hr =
130.515 mph
5th
R / T = 2323.330 RPM (at the wheels) * 60 min = 139,399.806 RPH (at the wheels)
Top speed = 139,399.806 RPH * 6.352 ft = 885,467.570 ft/hr =
167.702 mph
http://www.mazdas247.com/forum/showthread.php?t=86800&highlight=top+speed
Using GPS and Radar machines, a 215/45/17 tire is the most accurate in relation to our speedometers.