I have a 2019 F250 6.2 with 20" wheels and 4.30 gears. I'm trading it on a 2020 7.3 with 20" wheels. The 10 speed transmission really has me questioning which gear ratio I want. User ExxWhy shared a comparison of the 4.30 and 3.55 ratios with the 10 speed tranny versus the 2019 4.30 with 6 speed as follows:

4.30----------- 3.55 ---------4.30 with 6 spd

1 19.82 ----- 16.68----- 17.93
2 12.56----- 10.61------ 10.06
3 9.16 --------7.63-------- 6.54
4 7.61 --------6.39-------- 4.90
5 6.54 -------5.40--------- 3.74
6 5.50 -------4.54 ---------2.97
7 4.30 -------3.55
8 3.65 -------3.02
9 2.97 -------2.45
10 2.71 ------2.27
R 20.21 ----17.29 -------14.62

In looking at the gear spacing, wouldn't the new 10 speed transmission with the 3.55 gears, towing my 8000lb tag along, still provide more gears and shorter gear spacing as my 6 speed with 4.30 gears if I locked out 9th and 10th gear? I'd actually have 8 gears with shorter gear spacing than I have today with my 6 speed, no? And, it would allow me to cruise unloaded at 70mph at much lower rpm. What am I missing?

 

Yes it should do just fine and how you describe. 95% of the replies will recommend the 4.30 but if you look hard enough you will find users with the same 3.55RE that report solid performance at those weights. You will also find 3.55 and 4.30 users that say they get 16+ mpg so good luck with deciphering all of that BS. I bet you will find a 3.55RE with 20s on a dealer lot within reasonable driving distance so I would suggest test driving unloaded and see how it feels versus your current rig.

If you’re ordering then consider your driving circumstances:

mostly city, Lots of hills or mountains, towing over 10k more than a few times a year then I would order the 4.30 and wait

mostly highway, weekend warrior towing 8k and under, want a truck sooner rather than later. Get the 3.55 now and enjoy the hell of it.

JMO

 

Get the 4.30's. The 10th gear in the transmission is geared higher than the 6th gear in your 2019....meaning even with 4.30's, your RPM's will be lower on the 2020 truck compared to your 2019. With 4.30's...you might actually be able to use 10th gear without it downshifting on the tiniest of hills or smallest acceleration. 4.30's will also mean the transmission will do less gear hunting and shifting in general.

 

I don't think you are missing anything. The only place the 4.30 'outperforms' the 3.55 is in 1st gear starting from a dead stop. So up to a few miles per hour you have more torque available at the wheels. Anytime after that, and the 10 speed will be able to keep you close to the RPM sweet spot for the situation. With an 8K trailer it should be an easy choice. Plus with the 3.55 you get the benefit of the lower RPMs at highway speed. Unless you are pulling super heavy or insist on jackrabbit starts the 3.55 makes more sense to me. Take one for a test drive.

 

Decide what your priorities are for driving in all scenarios including your trailer 8k lbs. trailer. For the best MPG and putting acceleration as 2nd in prority, get the 3.55. To have better acceleration putting MPG 2nd in priority, get the 4.30's. Since you mention having a lower RPM at freeway speed, it sounds like MPG or lower noise is a priority so get the 3.55's.

 

Too bad the 3.73 isn't an option on the 250. I went with the 3.73 on my 350 because
A) it seemed like thats what all dealers had on the lots with the 7.3L setup.

B) It seemed like a good compromise between the 4.30 and 3.55

The truck has plenty of power, so I think either will be fine. But it seems the general consensus is the 3.55 on average will gain you 1mpg highway. 4:30 is better for towing heavy.

 

The 10 speed 4.30 will have a lower 1st gear ratio and higher final gear ratio than your 6 speed. Not sure what else you could ask for if you like your current truck. If you want a taller 1st gear and taller final gear than you have now get the 3.55.

 

Wrong.

The 4.30s will outperform the 3.55 in every gear.

It’s not like ‘ I turn the same RPM at 70 in 9th’

It’s like ‘I have a longer cheater pipe on this breaker bar’.

That’s why the 4.30s gives a 2-ton towing advantage in the same truck.

IMO, and I drove a few, 3.55s kills the 7.3.

 

I went back and forth with gearing when I ordered mine. I probably spent more time thinking about it than I needed to. Living in the PNW and doing a lot of in town driving vs mostly freeway driving, 4.30 gears with 20" wheels made more sense for me. It will run in 10th gear more often than not, even on a number of hills. At 75 mpg it runs at 2k rpm. I think 3.55s run about 1700 rpm. I also thought about if it down shifting with ever little hill on and off the freeway. I haven't driven one with 3.55 so IDK if that even happens. One thing to consider is even though you only tow an 8k trailer now, it's very possible down the road that you will get something bigger. It will do just fine either way, so like others have said, base it off of your situation and what your priorities are.

Gear Ratio Calculator

​​​​​You can use this to see what rpms it will run a any speed. Select the Ford 10r80 transmission, put in the rear end ratio and your tire size.

 

And just remember, Ford designs these trucks to keep the RPM's low, and shift into the highest gear possible as soon as possible. This all has to do with emissions and fuel economy. My truck (6R140) wants to be in 6th gear at 35mph Lower gears (higher number) helps greatly with this...like "samuse" said...a longer cheater pipe on the breaker bar. The engine works less.

 

The video linked below may be one of the better towing reviews of a 7.3L. The guy is pulling an 8,000 TT with F350 and 3.73's. Jump to the 4 min mark when he finally gets on the hwy. Truck loves 6th when it hits any small hill. With a 3.55, may be in that 5th or 6th range. May only get into 9th or 10th under flat or downhill. The guy just tells it like it is, let the truck rev when it needs to. I think with 3.55's you just need to expect your only going to be using only 7 or 8 gears in the 10-spd, but that's why all those gears are available for the different scenarios you may use it for. I too would prefer the 3.73 option more than the 3.55 behind the 7.3L. The 6.2L/4.30 combo is actually rated to tow more than the 7.3L/3.55.

 

Thank you all for the replies. I originally ordered my 2019 with 4.30s in the event I ever bought a 5th wheel. I was surprised that my 4.30s provided better fuel economy and a really good driving experience for 99% of my driving, even when not towing. I got better MPGs than my friend with 3.73s around town. But like many, I don't love the high revs needed on the hills when towing. Recently, I tested an F350 with the 7.3L, 18" wheels and 3.73s (all the dealer had), and I was so impressed by the immediate torque at very low RPMs. Barely had to touch the accelerator, and the truck got 15mpg on a short test drive.

The only reason I am giving it so much consideration, and posted this, is because of the 10 speed transmission and the wide array of ratios it provides. It would seem you can have your cake and eat it too. But Ford disagrees, because they assign they still assign the highest tow ratings to the 4.30 gears. I guess the final answer is to get the 4.30s and don't look back. My last 2 trucks were special orders. I have X Plan, and I love the experience of building exactly what I want and tracking the truck through the process.

 

I have to be honest. The 7.3L may be a great engine, but gassers just need to rev, and watching the video Wyo2Track shared makes me want the Power Stroke!

 

To each his own, I tow around 10-11k with 7.3 3.55 and it pulls real hard!

 

It ain't worth it!