calculations

[Fergusonic]

Tire Radius =TR

Gear Ratio =GR



Reg Trannys:



MPH=TR div.by 168 X RPM div by GR

RPM=168 X GR X MPH div by TR

GR =TR X RPM div by 168 div by MPH



700R4:



MPH = TR div by 168 X RPM div by (GR X .72)

RPM = 168 X (GR X .72) X MPH div by TR

GR = (TR X RPM div by 168 div by MPH) divby .72

[ZZ4Blazer]

Thats for??

[bohn333]

What the.......is that for?

[Fergusonic]

I\'m thinking of changing my rear gear ratio to a 2.72-1: I wonder what RPMs I would be pulling at 70 MPH?...or I wonder what MPH I will be going at 3000RPMs



My speedo seems inaccurate: I know my rear ratio, I know my RPMs...Oh...now I can calculate what my MPH really is.



etc etc

[Mike]

well it makes more since now.

[bohn333]

Now i get it http://www.s10v8.com/images/smilies/icon_wink.gif

[ZZ4Blazer]

http://www.sgmotorsports.com/mph.htm#GearSpeed



Or go here and don\'t do any math

[BadAss_2002]

Tell me if I did this right

For RPMs at 75 I came up with 1293.6

168 x 3.08x 75 divided by 30 for the tire diameter correct?

[martin777]

www.smokemup.com/auto_math/index.php (http://www.smokemup.com/auto_math/index.php)

[Fergusonic]

Badass-2002: your calculator did it right...but I must admit, Smoke Em is much better. I got the \"hand\" calculation formula from Summit a few years ago.