Axle ratio
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Tuned
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From: Creston, NC
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Tuned
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Rule of thumb is you lose .1 in gear ratio for each 1" taller tire you go. So you're going from a 34 to a 37, your 3.55 will be 3.25 effective. F250's come with 3.31 stock, so your basically right there. I wouldn't sweat it unless you tow really heavy frequently.
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Don’t fret the 3.55s. My 2020 F350 CCSB diesel has 3.31 and I tow a 14,000 lb 5th wheel. It does a great job win the 10 speed and 6.7L diesel.
I had a 2017 with 3.55s and a 2019 F350 with 3.31. The 2020 with 3.31s is a rocket ship compared to the previous trucks due to the extra power and 10 speed.
I had a 2017 with 3.55s and a 2019 F350 with 3.31. The 2020 with 3.31s is a rocket ship compared to the previous trucks due to the extra power and 10 speed.
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Don’t fret the 3.55s. My 2020 F350 CCSB diesel has 3.31 and I tow a 14,000 lb 5th wheel. It does a great job win the 10 speed and 6.7L diesel.
I had a 2017 with 3.55s and a 2019 F350 with 3.31. The 2020 with 3.31s is a rocket ship compared to the previous trucks due to the extra power and 10 speed.
I had a 2017 with 3.55s and a 2019 F350 with 3.31. The 2020 with 3.31s is a rocket ship compared to the previous trucks due to the extra power and 10 speed.
Hotshot
Joined: Jun 2003
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From: SW VA
Fuel mileage and emissions. 3.55's will still have the better actual performance...but we are only talking about 0.24 to 1 of a difference here. Nothing drastic.
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Back in MY 2017 and 2019 in order to get the 3.55 with 18" tires required that you also order Heavy duty front springs(HD option, Snow Plow or Camper option). My 2017 was purchased off the lot. I didn't like the ride f the HD front springs so when I ordered the 2019 the only axle available with standard front springs and 18:" tires was 3.31.
Ford agreed to Lemon Law (buy back) my 2019 due to an intermittent starting problem. . Before the buyback was finalized the dealer proactively ordered a 2020 with the exact same configuration of my 2019. So it was ordered with 3.31s even though in 2020 you could get 3.55.with 18" tires and standard front springs.
Now I will say that the 3.31 with the 2020 diesel is great. The transmission software logic will keep it in 9th gear at 60 mph if it is needed. I'm getting about 23 MPG at 60 MPH unloaded. About 11 MPG with the 14,000 lb 5th wheel in tow. The 2020 6.7 diesel is much more responsive and little turbo lag compared to the previous years.
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