P.O. Box 1169
#1 Hot Rod Lane
Mena, Arkansas 71953
U.S.A.
(479) 394-5711
(479) 395-7113
FINAL DRIVE RATIO FORMULA
(RPM) = 168 X (TR) X (MPH) / Divided by
1/2 of the Tire Diameter
(MPH) = (RPM) X 1/2 of the Tire Diameter
/ Divided by 168, then Divided by (TR)
(RATIO) = (RPM) X 1/2 of the Tire
Diameter / Divided by 168, then Divided by (MPH)
(TR) = Rear Gear X Final Transmission
Gear
EXAMPLE:
700R4 with .70 Overdrive, 26”
Tires, with 3:73 final gear ratio.
2193 (RPM) / 168 X 2.011 TR X 65 (MPH)
divided by 1/2 of the Tire Diameter of 13”.
BEST PERFORMANCE AND MILEAGE FOR A STREET
VEHICLE.
2000 to 2200 RPM while Driving 65 MPH to
70 MPH
WHAT GEAR RATIO IS BEST FOR TALLER TIRES?
Recommendations Based on Average Power
Curve of Most Engines in Direct Drive Gear of Standard
Transmission at 55 MPH
