The Ford Barn - View Single Post - 5 spd in a 37 pickup with a 4.44 rearend.

JSeery · 08-13-2019, 06:26 PM

RPM equals MPH times the Transmission Gear Ratio times the Rear Axle Ratio times the constant 336 all divided by the Tire Diameter.

RPM = (MPH X TGR X RAR X 336)/TD

You know the tire diameter size you are using so you can look up the diameter.
You know the MPH you want the RPMs at, 55.
You need to determine the Overdrive gear ratio for your transmission.
You know the Rear Axle Ratio, 4.44.

So, RPM = (55 X TGR? X 4.44 X 336)/ TD?

I don't see a 6.75 tire, but a 6.70-15 radial is 28.24 inches.

Assuming a V6, the OD ratio of a 1985 S10 T5 should be 0.70 (think that should be 0.72)

RPM = (55 X 0.70 X 4.44 X 336) / 28.24
RPM = 2034 RPM

If my math is correct, 2034 RPM

08-13-2019, 06:26 PM	#2
JSeery Member Emeritus Join Date: Nov 2012 Location: Wichita KS Posts: 16,132	Re: 5 spd in a 37 pickup with a 4.44 rearend. RPM equals MPH times the Transmission Gear Ratio times the Rear Axle Ratio times the constant 336 all divided by the Tire Diameter. RPM = (MPH X TGR X RAR X 336)/TD You know the tire diameter size you are using so you can look up the diameter. You know the MPH you want the RPMs at, 55. You need to determine the Overdrive gear ratio for your transmission. You know the Rear Axle Ratio, 4.44. So, RPM = (55 X TGR? X 4.44 X 336)/ TD? I don't see a 6.75 tire, but a 6.70-15 radial is 28.24 inches. Assuming a V6, the OD ratio of a 1985 S10 T5 should be 0.70 (think that should be 0.72) RPM = (55 X 0.70 X 4.44 X 336) / 28.24 RPM = 2034 RPM If my math is correct, 2034 RPM Last edited by JSeery; 08-13-2019 at 09:19 PM.