I was thinking of swapping my gears to gain some quick off the line power but I want to find a good ratio to go with. Does anyone have a formula to calculate the gear ratio or RPM based on the following parameters: overall tire height, transmission ratio in each gear, rearend gear ratio? I want to find out what RPM I will be pulling in each gear and how this will effect my speed in each gear. I will be running 18" wheels so my tire height will be around 27" in diameter. I drive my car on the highway a lot so I don't want to sacrifice too much by going with 3:73 or 4:10 gears. Any help would be appreciated.

Thanks, Josh

 

Go look at the front page of this site, there is a bunch of tech stuff on the left hand side, including exactly what you want.


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1991 Camaro Z28
5.7L 5-Speed (originally 305)
317 RWHP, 418 RWTQ
13.23 @ 107.62 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Member: SoCal F-Bodies
-=ICON Motorsports=-

 

Kevin-

Thanks for the info, that's exactly what I wanted!

 

use this

rpm = mph x gr x od x 336 / td
rpm = engine
mph = miles per hour
gr = gear ratio
od = overdrive ratio
336 = magic number that makes the equation work
td = tire diameter