# Tundra With 30 Ft Outback



## Liz C (Jan 21, 2012)

I have posted about our truck and trailer combo before, but needs some more advice. We are getting like 8pmg pulling the TT. I know we need to add air bags to help with leveling of the truck. I am going to off-load lots of things out of the rv, when we get ready to make our trip to Disney this summer.

This is my deal. My husband doesn't drive much, less than 150 miles per week. I owe about 2 more yrs on his truck. I really want to get his truck paid off and be without a payment. That being said, we are planning on Alaska summer 2014, we will need a new truck for sure. We use out tt about once a month within 100-125 miles from out home(one-way).

We have way to much crap in our tt. I am hoping that minimizing the stuff in the tt, that we will get better gas mileage to Disney.

I really don't want to get another truck, we would have to finance it and take on more debt.

Question and advice. Should we upgrade to a diesel this summer or wait until next yr for Alaska trip. It just kills me to see the gas gauge go down when we are pulling the tt. Is this mileage, normal or expected?

What else can I do to his tundra to increase the mileage?

Thanks,

Liz


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## ifd22 (Jan 18, 2012)

8mpg sounds a little low. I normally get 10 driving rolling hills through Kentucky. Best MPG was 12 through Ohio following a buddy who liked to drive @ 60mph. I normally drive right @65 mph using S mode on the transmission in 5th, manually downshifting to 4th on hills. The only time I've gotten 8 mpg is when I've left the transmission in drive using cruise control.

Not sure what speed you tow at but slowing down seamed to help a lot.

That being said, as much as I love my truck and how well it tows, I would certainly get a Diesel before towing to Alaska.


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## cdawrld (Jul 31, 2011)

You have the best idea for your current situation. Put your trailer on a diet. Take out all the "I might need this" stuff. Try a short trip with just the basics. See what you really need or don't. 
I travel with only 5 gallons water in the tanks. Remove one propane tank. Weight is directly related to MPG.


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## Northern Ninja (Aug 20, 2011)

We average 8-10 with ours as well. You'd have to tow ALOT of miles per year to make a diesel worth the extra money. You can add an aftermarket cold air intake and a pro chip/tune to get a couple more MPG, but realistically you can't expect a whole lot more than that from a truck pulling 8000#'s. We also have a 2500 Chevy with a 6.0 gas engine, and the fuel mileage is pretty much the same as the Tundra while towing.


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## TwoElkhounds (Mar 11, 2007)

I would say 8 to 9 mpg is about right if you are towing on hills or have a head wind. Easiest way to improve your gas mileage is to slow down. My unscientific calculations show that mileage at 55 mph is about 30% greater than mileage at 65-70 mph when towing. I have a diesel, so your numbers may not match exactly, but slowing down is the best thing you can do to improve mileage.

DAN


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## Danodog (May 19, 2012)

I average around 9mpg with a 20008 4x4 Tundra with the 5.7. I tow a 2013 250RS. I have had a low of 4MPG pulling the trailer up the Techapi grade and a high of 18 mpg going down the grade. LOL 8mpg sounds about right. I would like a diesel too, but I can't justify the cost.


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## Todd&Regan (Jul 1, 2010)

Northern Ninja said:


> We average 8-10 with ours as well. You'd have to tow ALOT of miles per year to make a diesel worth the extra money. You can add an aftermarket cold air intake and a pro chip/tune to get a couple more MPG, but realistically you can't expect a whole lot more than that from a truck pulling 8000#'s. We also have a 2500 Chevy with a 6.0 gas engine, and the fuel mileage is pretty much the same as the Tundra while towing.


In addition to removing unnecessary items in your tt, a custom air intake (such as K&N) plus cat-back performance exhaust, and a programmer/tuner (I would recommend Edge Products) not only will help your MPG, but also give you more horsepower and torque. All those items combined, you'd be looking at about $1000.....much cheaper than taking on a bigger vehicle payment. I'll be purchasing an Edge CTS this spring for my F-150 Ecoboost, which will give me 415 hp, and 473 ft.lbs. of torque in the towing setting.


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## Liz C (Jan 21, 2012)

Thanks y'all, I really think we are going to put the tt on a serious diet. This summer, we are only taking what we have to on the trip, no extras. I think I am going to take out the extra bunk matresses etc. I really want to buy a truck next yr, want to only have one payment. Good to know that others are getting about same mileage results as us. I am really estimating the mileage, next trip, I am going to calculate the mpg for our spring break trip.

Thanks,

Liz


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## Danodog (May 19, 2012)

Liz C said:


> Thanks y'all, I really think we are going to put the tt on a serious diet. This summer, we are only taking what we have to on the trip, no extras. I think I am going to take out the extra bunk matresses etc. I really want to buy a truck next yr, want to only have one payment. Good to know that others are getting about same mileage results as us. I am really estimating the mileage, next trip, I am going to calculate the mpg for our spring break trip.
> 
> Thanks,
> 
> Liz


Make sure you keep the speed limit at 55MPH. I can average almost 11 MPG on flat highways if I pay attention to the speedo.


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## Liz C (Jan 21, 2012)

I keep the speed at 55, just can't go any faster and see the gas gauge go down faster. I am so taking all the extra stuff out. Will put back in when needed. Just don't want to haul all this stuff around and pay to gas. I have a motorcycle trailer that I am going to off load the misc stuff onto, then add it back when needed. Looking forward to better gas mileage.

Liz


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## KTMRacer (Jun 28, 2010)

I think you'll find that weight isn't the dominant driver in your mpg. It's all the frontal area and drag and speed.

Weight has an big effect as you accelerate or go up a hill. On level ground and constant speed weight has only a minor effect on mpg. Remember, your pulling a "barn door" down the freeway along with two more axles with rolling resistance of two more axles.

Drag is related to speed (or engine rpm) CUBED!! So speed is big contributor.

As an example of the effect of weight, I have two trailers I tow with my duramax diesel. There are two routes that I take both on quite a bit and I've compared mileage. First the trailers. The smaller is a 7x14 cargo trailer, combined weight (truck and trailer) is right near 13,000 lbs. The second is my outback 8x35, and much taller. Combined weight (truck and trailer) is over 18,000lbs.

Now the routes.

1) sea level over a 5,000 ft pass and back, average mileage with the 7x14 is usually about 12.5- 13mpg, with the outback 11+
2) down the interstate, very constant speed, not much elevation change. 7x14 about 14 mpg, outback about 12.5-13
so you can see, 5,000 lbs difference is only a few mpg at best.

so, yes minimize your weights, it will help but don't expect a big change. Note that the 7x14 is 1' narrower and over 2ft shorter in height so it has a noticeably lower frontal area and less drag, which is a big contributor to the difference in mpg. With the same frontal area, I suspect the difference in mpg would be even less.

On the interstate, the difference between 60mph and 65 mph is consistently 2+mpg. so speed has a bigger effect for us than weight!

Dropping to 55 if you can stay in high gear is the best thing you can do. In my case on secondary roads I drop to 56-57 and that also makes a big difference. I need to stay slight above 55 or it will drop down to 4th gear.

And not knowing your terrain etc. it's hard to say what mpg to expect, but out here, folks I know with gas engines towing 25' plus trailers are getting in the 8-9 range. But we do have hills and some mountain passes.


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## Santa Fe TX Bob (Oct 30, 2011)

I'm glad I read this thread. It doesn't make me feel so badly. My prime mover is a 1999 Isuzu NPR HD with 4 liter diesel. I get a consistant 10mpg towing or not. The truck has a 14' box which shadows the wind from hitting the trailer. The advantage of using this truck is that it can handle the hitch weight without extra springs/air bags/equalizing hitch, there is plenty of room for bringing my own fire wood, and I can put the runaround car inside the truck as the load capacity is 6,000 pounds.

Bob


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## 4RovingSongsters (Jun 22, 2011)

Only one quibble: according to NASA the drag equation is D=Cd x r x(1/2)V^2 x A, that is, Drag is equal to the Coefficient of drag for the specific body and conditions, times r the mass density of the fluid (air), times one-half the square of the Speed through the fluid, times the reference Area of the front of the body. In short, the drag effort(force) varies as the speed squared, not cubed.

The power expended in pushing the air is this drag times the speed again, so it's the POWER that runs with the cube of the speed. But when you consider the time difference in arriving at the same distance at a lesser speed, the quantity of concern is energy, not power, so it's back to the square function. Neglecting other losses, the energy expended on aero drag for a fixed distance should be 26% less at 60 mph than at 70 (if you can stay in high gear). This translates to 12.6 mpg rather than 10. Again, that's neglecting hills, tire rolling resistance, residual braking effort, etc. The POWER reduction is greater (~37%) but you have to maintain it 17% longer at the lower speed. Your mileage will probably be less.


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## Santa Fe TX Bob (Oct 30, 2011)

By definition getting 12.6 miles per gallon is better than 10 miles per gallon. The time it takes to run those miles is not a part of the equation. Introducing the time factor into the mix just muddies the waters. Also the drag calculation you propose only considers frontal area. It ignores the shape of the unit that may reduce the drag by creating a smooth laminar flow of the fluid thus lessening the drag increase as the speed through the fluid increases. Rather than go throught all the girations of calculating the variables, most of us would rather do a few trips under various speeds and derive our figures through experimentation. Suffice it to say that it is becoming increasingly costly to drag our units down the road as fuel prices go thru the roof. No amount of air dams, laminar flow gadgets, or speed/wind resistance calculations can do anything about the cost of fuel. Southwest airlines/car rental/motel fees are getting more enticing. What we really need is more oil wells and pipelines. At 40 cents a gallon we would all be happy.


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## KTMRacer (Jun 28, 2010)

4RovingSongsters said:


> Only one quibble: according to NASA the drag equation is D=Cd x r x(1/2)V^2 x A, that is, Drag is equal to the Coefficient of drag for the specific body and conditions, times r the mass density of the fluid (air), times one-half the square of the Speed through the fluid, times the reference Area of the front of the body. In short, the drag effort(force) varies as the speed squared, not cubed.
> 
> The power expended in pushing the air is this drag times the speed again, so it's the POWER that runs with the cube of the speed. But when you consider the time difference in arriving at the same distance at a lesser speed, the quantity of concern is energy, not power, so it's back to the square function. Neglecting other losses, the energy expended on aero drag for a fixed distance should be 26% less at 60 mph than at 70 (if you can stay in high gear). This translates to 12.6 mpg rather than 10. Again, that's neglecting hills, tire rolling resistance, residual braking effort, etc. The POWER reduction is greater (~37%) but you have to maintain it 17% longer at the lower speed. Your mileage will probably be less.


good point on drag. I had a brain fade and was using cubed function for power relating back to the power needed to achieve a given speed, as in drag related top speed, instead of just drag related to speed. Thanks for the correction.


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