My F350 SRW 4x4 with 6.2L gas has a 3.73 axle and 18" tires. I carry a 9'6" NL truck camper which puts me at about 11,000lbs total.When cruising at 70mph, I turn 1,800rpms in 6th gear, and 2,300rpms in 5th gear. On a mild up slope the engine seems fine in 6th at 1,800rpms (e.g. I don't get any odd sound or sensation of lugging).Is there any thought on what a good rpm is for the engine and transmission when towing a load? With my prior 1997 Ford Expedition, the TOW button would disable the highest gear (OD).I also plan to upgrade to a slightly larger 18" tire so I can go from 3,640 to 4,080lbs per tire, and estimate 6th gear will drop to 1,700rpms, and 5th to 2,200rpms. I wonder if I will want to purposely avoid 6th?Thanks,--SiletzSpey

No idea what ideal might be, but 1800 seems pretty low if you can do it. Lower is generally better MPG, and I doubt that the electronics will let you go lower than you should.One thing to consider is a tuner. Then, you’ll have more control over shift points and can update your speedometer to work with the bigger tires. But, it might be possible that a slightly larger tire just makes your speedometer dead on.

Install a vacuum gauge. With a gas engine the vacuum will give you an indication if you are lugging the engine. Go with the gear that will give the best vacuum.

My 6.2 F350 in carry the camper mode runs same rpm as OP said. If head or cross wind has it shift from 6 to 5 a lot I select to limit top gear to 5. It sometimes choose gear 4 and runs along at 2500 rpm for miles. It never sounds like it is “lugging” or frantic, seldom revving above 3500rpm unless you apply lotsa throttle. This is on 87 E10 gas.This would be a super fun engine if it had “EcoBoost” stuff.The cruise control allows more mph drop before downshift than I like. I can get it to hold speed and not shift in manual throttle mode.I’m going to try some 91 gas once I get road tripping. A friend tows with a 5.4 Ford and the engine management likes 91.

I usually recommend close to the rpm associated with the peak torque rating.Maybe a little lower if lightly loaded and a little more if running heavy.

Ideal V8 rpms when towing? | Good Sam Community

Siletzspey
Explorer
Oct 10, 2019
Thanks for the replies!

I realized after asking that there is a miles-per-gallon optimization aspect, and a wear-and-tear optimization aspect, and I was thinking more of the latter.

I guess I've gravitated towards the answers that suggest the transmission and computer will choose a reasonable gear for all concerns. I do use the UP and DOWN arrows to set what top gear is allowed when 5-6 jumping occurs, and when going downhill.

Thanks,

--SiletzSpey
theoldwizard1
Explorer II
Oct 09, 2019
Siletzspey wrote:

When cruising at 70mph, I turn 1,800rpms in 6th gear, and 2,300rpms in 5th gear. On a mild up slope the engine seems fine in 6th at 1,800rpms (e.g. I don't get any odd sound or sensation of lugging).

Is there any thought on what a good rpm is for the engine and transmission when towing a load? With my prior 1997 Ford Expedition, the TOW button would disable the highest gear (OD).

My old E150 was the same way. I would frequently disable OD when approaching a hill so that it would not lug down too low before it kicked down itself.

The newer Ford 6 and 10 speed transmissions are computer controlled and the engine should not lug down too low. I am sure there is a way to manually shift it. If you manually put it in 5th, it is going to stay there forever, even when you slow to a stop, unless you shift it or put it back in full automatic.
Kayteg1
Explorer II
Oct 09, 2019
When new computer programs adjust the gears torque-wise, they lack intelligence to plan for engine cooling on long grades.
It was common on older heavy sets that well pulling engine will overheat 1/2 the way up the mountain and easy prevention was force it to drop couple of gears when starting and not going faster than 1/2 throttle.
This way higher rpm with less load provide for better engine cooling.
Same going downhill, when even with engine brake and speed controlling program, you might face situation that will call for more downshifting.
valhalla360
Navigator
Oct 09, 2019
specta wrote:
Transmission selector in D, tow haul button engaged.

Let the truck decide what's best. :D

Yep, with modern trucks, the engineers have sorted out which gear the transmission wants.

Now if you have an older truck or manual transmission, it's valid question.
specta
Explorer
Oct 09, 2019
deltabravo wrote:
Kayteg1 wrote:
Each engine has it "sweat spot"

My Duramax doesn't sweat

:D :D :D :D

Neither does my 6.0. ;)
specta
Explorer
Oct 09, 2019
Transmission selector in D, tow haul button engaged.

Let the truck decide what's best. :D
Bert_Ackerman
Explorer
Oct 09, 2019
time2roll wrote:
I usually recommend close to the rpm associated with the peak torque rating.
Maybe a little lower if lightly loaded and a little more if running heavy.

Op is talking about cruising and slight grades, depending on the year of the 6.2 you usually recommend doing that at 3800 or 4500?
deltabravo
Nomad
Oct 09, 2019
Kayteg1 wrote:
Each engine has it "sweat spot"

My Duramax doesn't sweat
MORSNOW
Navigator III
Oct 09, 2019
It's RPM (Revolutions per minute)as in the number of turns in one minute. Not RPMS (Revolutions per minutes), we have no idea how many minutes you are talking about.

Lower RPM does not always give the best gas/fuel mileage, you can lug an engine down too low and hurt your mileage. Depending on your load, the sweet spot can change for the best mileage.
jaycocreek
Explorer II
Oct 08, 2019
Keeping the mighty 460 to 2,000 rpms,makes it sip gas....Luckily,most of the roads I travel have 45-60 mph speed limits...4.10 gears has it zipping up the hills like there not even there..Faster than a speeding bullet and more powerful than a locomotive ...

The 460 Ford(Laughing)