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Old 03-01-2014, 10:05 AM   #1
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Fuel economy question

I've got a question for those of you that stepped up from a TT to a 5er. I came from a Springdale 286RLDS, 6500 dry weight TT, basically flat nose, rippled aluminum siding. 15" E range radial tires with 80 PSI. Towing that on the highway I got 11MPG.

Now I have my 5er, Sierra 346RETS and it's got the modern aerodynamic bullet nose that lines up nicely with my truck cab, smooth hard siding, 16" radials (I think they're radials, I haven't looked actually.) set at 80PSI.

This one has a dry weight of 11,345, a 4800 pound difference. I pulled it with the same stuff that was in the TT so we're on equal footing regarding payload above dry.

I had a 3/4 full tank of fuel, pulled the old one to trade 90 miles, hauled the new one home the same 90 miles except this time was in heavy traffic. I then hauled the new one 60 miles to have a break in weekend. I needed to fuel up to go home and found something shocking.

I pulled 13 MPG down. From experience I know I got 11MPG pulling the TT to trade. I also know I got 19MPG for the 80 or so miles I ran around with it empty. Even subtracting those miles I got 11.5MPG between the two campers.

I now wish I had filled it up for a fuel economy run.

My question is, has this been your experience? I know this one is much more aerodynamic but I figured the weight would put a bigger penalty on me.

Did you pick up fuel economy by going with a more aerodynamic, but much larger and heavier, 5er? I'm perplexed. I see a dedicated fuel economy experiment in my future.
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Old 03-01-2014, 11:32 AM   #2
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We seemed to have similar results. F250 CC 4x4 V10 is our TV. Had a 30'tt, aluminum sided, round front and got 7 mpg at 7K loaded weight. Now tow our Sabre 34tbok, 40'long, 13,200lbs and still get the same 8 mpg? Sometimes better too

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Old 04-11-2014, 07:31 PM   #3
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Sounds about right, we've been getting 14 Mpg pulling our 355QBQ with our Diesel P/U.
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Old 04-11-2014, 09:44 PM   #4
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I actually forgot about this thread, thanks for bringing it up!

Gave it a not so hot mileage run, I ended up in stop and go traffic for about 25 of 80 miles but still managed 10.35MPG. I'm ecstatic! I'm hoping that pulling it to camp tomorrow will be smoother traffic and will allow me to find out what she'll actually do on the highway but knowing I haven't lost ground makes me really happy!
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Old 04-19-2014, 01:28 PM   #5
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I pull a little fast, up to 78MPH if the speed limit is 75. I was surprised last year to get just over 9 with our 365SAQ and our 2011 Duramax. I had already brought up to the dealer that I wasn't getting the mileage with our 2011 we got with our 2008. They asked me to put some more miles on the truck and break it in a little. The truck generally doesn't go anywhere without the camper (maybe a Home Depot / Lowes trip or two but that's about it) It took 3 years but we're finally getting decent mileage, especially for weight and speed.
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Old 04-19-2014, 01:42 PM   #6
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I pull a little fast, up to 78MPH if the speed limit is 75. I was surprised last year to get just over 9 with our 365SAQ and our 2011 Duramax. I had already brought up to the dealer that I wasn't getting the mileage with our 2011 we got with our 2008. They asked me to put some more miles on the truck and break it in a little. The truck generally doesn't go anywhere without the camper (maybe a Home Depot / Lowes trip or two but that's about it) It took 3 years but we're finally getting decent mileage, especially for weight and speed.
You are lucky you didn't blow a tire as they are only rated for 65 max. Towing that fast you are just asking for trouble.
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Old 04-19-2014, 01:46 PM   #7
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You are lucky you didn't blow a tire as they are only rated for 65 max. Towing that fast you are just asking for trouble.
Have to agree but I'm continually amazed at how many 5er's I see being pulled at 75 MPH on Western interstate highways. I clocked one once at 85 MPH and he also had a boat behind the 5er. Every now and then I run across one laying on its side in the median . .
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Old 04-19-2014, 09:01 PM   #8
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You know.... I don't remember seeing anything about a max speed on the new tires, I checked them over pretty good after they were installed. I would also think I would have remembered something about a max speed rating. I'm the toe of person who would have raised some serious concerns over that however, I will check after church tomorrow as I'm very curious. Someone else had also mentioned something about a speed rating, maybe it was in this thread, maybe in another. If it says a max speed, I've got no problems slowing down, if it doesn't, you'll see me in the fast lane. I don't need to be going faster then anyone else, and I'm not in a competition, but when you've only got 1 week's worth of vacation, you can't take 2 days to go on a 600 mile trip. You wouldn't have any time to enjoy the vacation.
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Old 04-19-2014, 10:08 PM   #9
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All ST tires are recommended to go no faster than 65, though Goodyear Marathons claim they can go 75 if inflated 10PSI over recommended pressure, not to exceed wheel or tire max pressure. Will the world end if you're running 70? Nah. But pop a tire running 78 and even touch another car? The police will most likely note it on the report that you were near 80, once witnesses speak up. Your insurance will go ballistic over that info. Gotta remember, they have lawyers that will exploit that one point and make it your fault, even if the crash isn't your fault, even if you ran over something that cut the sidewall out.

Physically I have no qualms running up to 75 to get around slower traffic, but I always keep the liability aspect in my mind.
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Old 04-19-2014, 10:30 PM   #10
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when we had a 30ft TT that looked like a ski slope (timberlodge 30sky) I only saw 9-10 pulling it with a camper shell installed, then we got a freedom express TT 298reds and I saw the same mileage, my father inlaw has the exact same truck but in the GMC trim and he always saw 11-12 pulling his 38ft designer jayco, when we got our 5er we see 12.5 all day @65mph in the hills or not. I think areo has a lot to do with better mileage in the 5er
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Old 04-19-2014, 11:12 PM   #11
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All ST tires are recommended to go no faster than 65, though Goodyear Marathons claim they can go 75 if inflated 10PSI over recommended pressure, not to exceed wheel or tire max pressure. Will the world end if you're running 70? Nah. But pop a tire running 78 and even touch another car? The police will most likely note it on the report that you were near 80, once witnesses speak up. Your insurance will go ballistic over that info. Gotta remember, they have lawyers that will exploit that one point and make it your fault, even if the crash isn't your fault, even if you ran over something that cut the sidewall out.

Physically I have no qualms running up to 75 to get around slower traffic, but I always keep the liability aspect in my mind.
Not sure what the speed limits are in Georgia, in Nebraska and South Dakota, most speed limits are 75mph, and in Colorado, 70. Now I know I said I run up to 78 when the speed limit is 75, because I will often go 2-3 over but I just called my buddy, a Douglas County Deputy and he said... there's a lot of if's, but If there was an accident, and if my tires have no mention, right on them, where the owner can clearly see, stating I have to drive slower then the posted speed limit, I would not be at fault. I'm not trying to debate this issue, nor am I trying to skirt the issue that an accident at that speed could easily kill someone, heck, an accident at 25 MPH could kill someone, a pedestrian j-walking into traffic at 25mph will kill. If you don't feel comfortable driving that fast, or if the tires you are running clearly state not to go over 65, don't go over it, but don't get upset with someone's who tires don't mention it (although I have to check tomorrow, but once again, I know how fast I drive, and I just had new tires and axles installed last spring, I looked them over and over, I'm pretty sure I would have brought this up to the dealer) There's also something to say for some of the folks who go too slow. They cause traffic jams, sometimes causing people to slow at an erratic pace to keep from running into them. When you're going 60 or 65 and semi's are passing you running 75 or more, the amount of push you get from them passing is awfully significant. They push you way out onto the shoulder, and yes, when they pass you suck back into your lane, but get someone not expecting that and overcorrecting and you could have an accident. In Nebraska we have some speed limit minimums. They do this to keep people from getting into accidents. You have to be able to move with the flow of traffic.
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Old 04-19-2014, 11:45 PM   #12
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Ga has a 70MPH limit, 45 minimum. When you go outside, you'll likely see ST235/80R16 or whatever size tire your rig has. The ST is the designation, no more than 65.

So yes, your tires have it, right on them.

This is what I found through Google, it's first thing mentioned under speed.

Trailer Tire Facts - Discount Tire

You can what if all you want, you can give me the scenarios and how unsafe it is to be traveling slower than traffic. Fact is, your buddy is wrong. All tires have the speed designation right on the side of the tire in the form of a letter code, in car tires it's something along the lines of 107H. 107 refers to a line on a chart that is it's load rating, H is the designated max speed which for discussion sake is up to 130MPH.

But in the case of trailer tires it's the ST, or Special trailer, in front of the size.

Try all you want, but there's no way out of this. You either don't have trailer tires, or you're going to find ST on there and you're handcuffed.
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Old 04-20-2014, 12:56 AM   #13
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I have gotten as high as 16 MPG. My trailer is only 7400lb dry. Also this is my third trailer, the first one was shaped like a brick - a huge wind drag at anything over 65mph. With a 7.3 the best it got was 10mpg and it only weighed 5500 dry. The next time I tried a "V-Nosed" trailer (Keystone VR1 at 7600lb dry) that helped the milage with same 7.3 went up to avg of 12mpg in spite of it being heaver than the first one. Then I got a Cummins 5.9 and the "V-Nose VR1" milage went up again to around 13.5 avg. So on trailer no 3 - with the lessons I learned - I went with a lower profile and aerodynamic shaped 5th wheel. Now with the 5.9 pulling a 7400lb dry 5-er I can get 16mpg if I keep it around 60mph. (15mpg at 70 or less).
My lessons were (on flat ground at least) weigh was less of a factor than wind resistance for me. But now when I get in the hills (like my last trip in the Ozarks) I have to admit my mileage dropped a couple MPG.
I use cruse on flat ground (not in the hills).

My current rig with the aerodynamic nose and lower roof profile than most so it is not up in the wind so much.

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Old 04-20-2014, 06:56 AM   #14
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Originally Posted by SKnight View Post
Ga has a 70MPH limit, 45 minimum. When you go outside, you'll likely see ST235/80R16 or whatever size tire your rig has. The ST is the designation, no more than 65.

So yes, your tires have it, right on them.

This is what I found through Google, it's first thing mentioned under speed.

Trailer Tire Facts - Discount Tire

You can what if all you want, you can give me the scenarios and how unsafe it is to be traveling slower than traffic. Fact is, your buddy is wrong. All tires have the speed designation right on the side of the tire in the form of a letter code, in car tires it's something along the lines of 107H. 107 refers to a line on a chart that is it's load rating, H is the designated max speed which for discussion sake is up to 130MPH.

But in the case of trailer tires it's the ST, or Special trailer, in front of the size.

Try all you want, but there's no way out of this. You either don't have trailer tires, or you're going to find ST on there and you're handcuffed.
I needed/wanted more of a safety margin as far as weight and a little speed. Not that I use speed that much, but wanted a cushion. I put Goodyear G614s on my camper and love them. Yes, they are LT tires and that subject has been beat to death, but those that have switched to LTs never go back. Remember, load rating first in my opinion. Getting there is part of the fun Yep, Georgia's limit is 70 now most anywhere on interstates and 65 on divided highways. I knew I was pushing my luck with with the ST rated tires. Now I have the cushion I wanted.
Back on topic here. Towing the camper in my sig, I get around 10.5-11 with my new truck. With my previous "10 6.4L, I got around 8 not matter where I went. The high profile 5ers really hurt fuel economy no matter the weight.
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Old 04-20-2014, 07:12 AM   #15
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I went from 9MPG pulling our 30ft bumper pull with a dry weight of 7000, to 12+ with our new 5th wheel that is 38ft with a dry weight of 11,000. I expect to get even better with time, as my truck only has 4000 miles on it.
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Old 05-07-2014, 06:24 PM   #16
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We went from 11.2 mpg pulling a 2011 FR V-Lite to 14.3 mpg pulling the new 2015 Sierra 330RLS. The V-lite was around 8,000 lbs and the Sierra is around 11,000 lbs. But the Sierra is a lot easier pulling than the V-lite and the 5th wheel has more room than the V-lite.
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Old 05-07-2014, 06:40 PM   #17
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14.3? Wow, I'd love to score that!

Seems I'm right in about 11. I got 11.8 so combined with the 10.35 I got with that stop and go mixed in I'm at about 11. Makes trip planning easy, calculate the miles, divide by 10. Then multiply by $4+
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