Berky
Middletown, DE
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Joined: 03/31/2012
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On our last trip I inadvertently left the tranny's tow/haul mode of on the return trip. Only picked up my mistake when I casually checked the tranny temperature and saw it higher than I expected, by about 10 degrees. To me, that higher temperature means the tranny is working harder and suffering more. You have my vote.
Mike, Barb, and Lilly the Lab
2012 North Trail 26LRSS
Silverado 2500HD, 6.0L gas, 4.10
Roar Like A Lion, But Fear The Hen
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Huntindog
phoenix arizona USA
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Joined: 04/08/2002
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Bedlam wrote:Huntindog wrote:75MPH. Life is short and I'm busy. Got things to see and people to do. 
You're right. Life is too short to put others at risk. What makes you think that your driving skills and equipment are so far superior to the standards and limits?
LOL. In AZ 75MPH IS the limit. And it is my standard. I drive in the high speed lane with the flow of traffic.
Huntindog
2010 Palomino Sabre 30BHDS
TWO bathrooms...No waiting!
MICHELIN XPS RIBS LRE
2011 Silverado Big Dually 3500 4x4 CC D/A
EQUALIZER Hitch
100% BOONDOCKING
Check out Rusty and her pups at www.bluecollarbrittanys.com
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Turtle n Peeps
California
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Joined: 06/23/2008
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venicite wrote:After years of pulling a travel trailer and a fifth wheel, I now am in a disagreement with my brother over towing speed. I have been of the opinion that keeping a moderate RPM over a long haul was better than a slow speed and geared way down. Any of you have a good argument either way?
Ya, I have an argument.
I put my D/A in drive; and drive the limit. If I need to make time I drive over the limit and if I need the fuel mileage I drive under the limit.
Works for me for over 30+ years. I don't worry what others do. I have enought things going on in my life to worry about what someone else does or how fast they tow or how they spend their money.
~ Too many freaks & not enough circuses ~
"Life is not tried ~ it is merely survived ~ if you're standing
outside the fire"
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Searching_Ut
Utah
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Joined: 05/09/2011
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It's interesting to see how many people supposedly tow slowly. I've found around here if you set the cruise control at 70 mph you'll be about average on the freeways when compared to the semi trucks and RV's. At 65 you'll rarely if ever pass an RV or Semi truck unless it's pulling a hill, but you'll get passed fairly often. At 75 you are mostly passing the other trucks and RV's, but you'll still be around average for cars, which generally seem to be doing between 75 and 80 for the most part, even on the sections of road where the speed limit is 80.
What surprises me the most is how many semi trucks you see running at 70 or higher.
Regarding the tires, as far as I recall it's only been fairly recently that ST tires were only rated at 65. You used to always just look on the chart to adjust the tire pressure for the load and speed you expected to be running at. Of course you would get a tire with the load capability to do what you wanted instead of having the marginally rated tires they seem to put on trailers now. On most trailers you have to negotiate better wheels and tires as part of the deal so that you can be safe even at slower speeds. The concept still works today you just get a higher load rated tire/wheel combo and run it about 10 psi higher for the given load than what is called for at the 65mph rating.
As for sweet spots, I have a couple on my truck both empty and towing. I get a sharp drop just over 50mph towing, then it's pretty much the same mpg up until around 65 where I get another sharp drop with a steep decline for every bit above that.
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hotpepperkid
Chino Hills CA
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Joined: 03/29/2002
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2000 RPM's is the sweet spot for my truck. With my gearing that mean 68 MPH. When I get below 1800 in the hills it shifts a lot so I keep it at 2000 or better. I have tried that 60 MPH thing, fig I would rather buy fuel than trans rebuilds. The wind is a bigger killer of fuel mileage than speed
hpk
2000 Ford F-350 SRW 4X4 PSD Jayco Super Lite 29.5RKS (31') 5th wheel 50 gal X-ferflow in the bed tank. Banks big exhaust and Stinger kit.
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Softballdad
Chesapeake, Va
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Joined: 01/05/2008
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I've tried driving at 55, 60, and now 65-67mph. My mpg is the same 8-10 no matter the terrain, so I set cruise at 65-67 and roll.
JOB 1 '08 F-350 4X4 LARIAT CC 6.4 DRW 4.10
B&W COMPANION 5TH WHEEL HITCH
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FORD MOBILE EASE HANDS FREE SYSTEM
08 HEARTLAND BIGHORN 3670RL
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wilber1
Abbotsford B.C. Canada
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Joined: 12/16/2002
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For mileage, generally the lowest speed you can go in the tallest gear but that can also result in the truck shifting down more often on slight grades as it isn't producing enough power to hold top gear. I usually cruise a little faster in rolling country than I do on the flat for that reason.
Cruising at 70 is the same as cruising at 60 with a 10 mph headwind. Don't tell me headwinds don't affect mileage.
"Never trust a man who has not a single redeeming vice" WSC
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JiminDenver
Denver, Co
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Joined: 09/09/2011
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On the flat I like 60-65. In the mountains it's what ever that speed warning on the next curve is. No reason to let the speed build up just to have to hit the brakes coming into the curve.
I learned about MPG and high speed our first trip out. I had no idea about the tires speed rating so when I jumped on the expressway I kept up with traffic around 75 MPH or so. The rig was rock solid and the Expedition has more than enough power so we were happy campers. That is until I looked at the gas gauge at the campground and we had gone thru half a tank of gas in 80 miles resulting in 5 MPG. What's amazing is how many rigs passed us doing 75.
2011 GulfStream Amerilite 25BH
2007/2003 Ford Expedition
Nights camped in 2011 21
Nights camped in 2012 16
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fandango49
Severna Park, Maryland
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Joined: 07/01/2011
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Using streets and trips I did two mock trips of 1,600 miles
estimated the speed setting slow abouty 55, fast about 65
my rig uses 9.5 mpg at 65 and 11.5 at 55.
outcome was I would arrive 3hrs sooner at 65 but cost about $115 more
figuring 3.85 per gal and twenty minute fuel stops
I drive average of 60 MPH
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Jayco-noslide
Galesburg,Il., USA
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Joined: 11/24/2004
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About the sweet spot myth, I would challenge anyone with any vehicle to drive 1000 miles at 70 and 1000 miles at 55 and compare the MPG or you can choose slightly different speeds as long as they are far enough apart to really measure a difference. The low speed is always going to win as long as it isn't so low as to drop the trans down out of the top gear. I think people think their engine has a "sweet spot" because they are used to driving at a certain RPM range and like the way the engine sounds. If they slow down, the engine may seem to "lug" a little so the thought is that it will use more fuel. I don't think so. I don't think you will get better MPG at 65 than you would at 62 or 60 but the difference might be difficult to measure.
Jayco-noslide
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