I have read a lot of posts relating to gearing but not exactly the info I am looking for so this is what I am searching for if anyone can help
original :2005 F150 4x4 5.4l Lariat automatic 3.73 gears with 285x65-18 tires (roughly 32.5") I do occasional towing of a 10K trailer any helpful info would be great
.70:1 4th gear ratio

**looking for info for 4.10 & 4.56 gears ** @ with about 34" tires

ball park MPG city/highway & engine RPM @ 70 mph

Thank you

 

According to our calculator, with zero overdrive, the 4.10 yields 2967 rpms, the 4.56 yields 3300. Not knowing what transmission you have or the overdrive ratio, I can't put that info in the calculator. Once you determine the overdrive ratio, multiply it times the rpms and viola, yer answer for it in OD. Gas mileage, take a wild guess. It'll be just as accurate as anybodys guess.

 

3rd gear is 1:1, 4th(OD) is .70:1

also if you could the 32.5" and 34" tires

thanks

 

Calculator:

http://4lo.com/calc/gearratio.php

Use 1 for transfer case ratio unless you want to calculate in 4 lo.

 

thank you about what I calculated for the increase

 

If you know what rpm it's turning now multiply that by 4.10/3.73 or 4.56/3.73 to find the new rpm. The same thing will work with changing tires. New diameter/old diameter x existing rpm at any given speed to find out what the new rpm will be. Simple math.