3.73 & 4.30 Axle Ratios - RPM vs MPH (calculated)

UTEngineer

Tremor Fiend
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2021 Ford F-250 Lariat 7.3L w/ Tremor & Blackout Packages
Current Ride #2
2017 Polaris General 4-Seater w/ Tailpipe Turbo
Was calculating numbers for work last week and decided to take a minute and calculate the difference in RPM at 60, 70, 80 MPH for a 3.73 vs. 4.30 axle ratio. (in 6th, 7th, 8th, 9th, 10th gears)

Kindly let me know if I screwed anything up ... have not had a chance to double check my calculations (nor have I verified them driving on highway).

3.73 vs 4.30.jpg
 
Was calculating numbers for work last week and decided to take a minute and calculate the difference in RPM at 60, 70, 80 MPH for a 3.73 vs. 4.30 axle ratio. (in 6th, 7th, 8th, 9th, 10th gears)

Kindly let me know if I screwed anything up ... have not had a chance to double check my calculations (nor have I verified them driving on highway).

View attachment 46110
Very interesting! Thanks for calculating and posting!

I’m surprised the difference is so small in 10th gear, regardless of speed. Pretty cool as it means we aren’t leaving a huge amount of highway cruising economy on the table by being forced into the 4.30 gears. Though climbing and towing are a bit of a different story. 500 RPM is pretty significant when in the lower gears.
 
As somebody with 3.73's, I'd say these numbers are accurate. Even with the MBRP exhaust, 10th gear cruising is nice and mellow.
 
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Wish they would offer 3.73’s for the diesel perfect truck gear imo (for diesels)
 
A Tremor with 34.8" tires and 4.30 gears is roughly the same as a FX4 with 33.2" tires and 4.10 gears. The 4.30 on my FX4 is probably overkill for my use case, but I had my mind made up on wanting the Dana axle. The mpg cost is minimal under 70 mph, and most of my driving is under 60, so I figured why not.
 
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