Trailer with 3.31 vs 3.55 Axle Ratio

[F150Eh]

Hey all,

I'm going to be towing a 6000+ lb trailer this Summer and I have a truck order to be built with 3.55 axle ratio. It's in KC though, so 4 week shutdown + no confirmed build date has me looking at on-lot options at my dealer just in case. They have one with the same 3.5L V6 engine and towing package but its a 3.31 axle ratio. GCWR is the same for both based on the Ford towing guide. I am new to towing and truck owning, so is there anything that would be of concern moving down to the 3.31 ratio?

Appreciate any comments, thanks!

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[Tosh]

I guess the main thing is you'll be turning lower RPM with the 3.31, and you might have to downshift more that if you had the 3.55.

What you might want to look at is the front surface area of your trailer. Tall, or low profile? this could make a big difference with a headwind. Ford includes recommended frontal area in their towing guide

 

[boy racer]

My .02 cent opinion so take it for what it's worth. Normally, the 3.31 would get you better gas mileage, on highway. But, with the 3.55 you will get a bit more pulling power so less time at higher RPM to get your trailer moving and when going uphill. If most of your towing is flat highway, the 3.31 should do you fine. Again, this is based on my basic knowledge on how differential gears work. I am not a mechanic or engineer.

 

[mustanga10]

My last truck had 3.31 gears and I have a similar sized trailer... my 2021 lariat has the 3.55 gears with 3.5eb engine with the max tow. My last truck did good but my new one does great. Last time I settled for my truck and got what was available. I am so glad I found what I really wanted this time, much happier with its performance and with the truck in general. So it probably won't make that big of a difference if rear end gears are the only thing that is different. But don't settle...

 

[Super Guest]

Ford is very good with the fine print in their online towing guides, so be sure the truck has all the options it needs to make that tow rating, otherwise the tow rating will be much lower because of the absence of the tow packages. And don't expect the dealer to be forthcoming with that information, or, at least they weren't when I was buying.

That said, I have a 3.5EB with the 3.31 rear and tow a 6200 pound TT all around the northeast and its far and away the best towing vehicle I've ever used; my old tow rig was a 2004 f350 6.0 diesel. I would say unless you are planning to approach max tow rating or are in high altitude, the 3.31 would be fine- just my opinion. But get the truck you want.

 

[F150Eh]

Thanks for all the comments everyone. Since my original post I'm looking at lot stock even more (KC shut down through May, June 7th is the earliest the truck could be built). There's one on the dealer lot that's also 3.73 axle ratio but uses the V8 engine instead of the V6. Better axle ratio, but lower overall towing maximums, although I feel like I'm being a bit paranoid that having 1000-2000 lb buffer after working out all the GCVR/GCWR math is "too close" when its likely more than enough wiggle room.

 

[Tosh]

V8 + 3:73 = no towing problems, but say goodbye to your fuel economy when you're not towing because you'll be turning higher RPMs.

However, it will probably do great burn-outs!

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